Calcium homeostasis in normal pregnancy and puerperium. A longitudinal study

Abnormal Calcium Levels are Associated With Worse Maternal and Fetal Outcomes; Results From an Exploratory Study

CONTEXT

Precise estimates of the incidence of hyper- and hypocalcemia in pregnancy are unknown. Abnormal calcium levels have been associated with unfavorable pregnancy-related outcomes.

OBJECTIVE

Determine frequency of hypercalcemia and hypocalcemia in pregnancy when tested and their associations with maternal and fetal outcomes.

DESIGN

Exploratory retrospective cohort study.

SETTING

Single tertiary care maternity unit.

PATIENTS

Pregnant women with expected delivery date between 2017 and 2019 and a second additional cohort of pregnant women with hypercalcemia between 2014 and 2016 and 2020 and 2021.

INTERVENTIONS

Observational.

MAIN OUTCOMES MEASURED

(1) Incidence of hyper- and hypocalcemia when calcium tested; (2) maternal outcomes: incidence of preterm delivery, emergency cesarean section, and blood loss during delivery; and (3) fetal outcomes: fetal loss (miscarriage/stillbirth), neonatal intensive care unit admission, and fetal birth weight (for term deliveries).

RESULTS

Total number of gestations and livebirths recorded were 33 118 and 20 969, respectively, with median [interquartile range] age of 30.1 [25.6-34.3] years. A total of 15.7% (n = 5197) of all gestations had albumin-adjusted calcium tested, and incidence of hypercalcemia and hypocalcemia when tested was 0.8% (n = 42) and 9.5% (n = 495), respectively. Both hypercalcemia (including additional cohort n = 89) and hypocalcemia were associated with increased incidence of preterm delivery (P < .001), emergency cesarean section (P < .001 and .019), blood loss (P < .001), and neonatal intensive care unit admission (P < .001). A total of 27% in the hypercalcemic group had an established diagnosis of primary hyperparathyroidism.

CONCLUSIONS

Abnormal calcium levels during pregnancy are common and associated with worse pregnancy-related outcomes, which raises the possible need for routine calcium testing. Prospective studies to confirm the incidence, etiology, and effects of abnormal calcium in pregnancy are recommended.

[Diagnosis and management of primary hyperparathyroidism during pregnancy: A systematic review and a longitudinal case study]

OBJECTIVE

There is no specific recommendation for management in pregnant women: the aim of this review, based on a clinical case study, is to clarify its development, complications, risk factor and treatment.

METHODS

A review of the literature was performed by consulting the Pubmed, Cochrane Library, and Science Direct databases.

RESULTS

Primary hyperparathyroidism is defined as excessive production of parathyroid hormone resulting in hypercalcemia. The prevalence of primary hyperparathyroidism during pregnancy is not known. Indeed, the symptomatology, related to hypercalcemia, is not very specific and easily confused with the clinical manifestations of pregnancy. The physiological changes specific to the pregnant state frequently lead to a slight hypocalcemia which may complicate the diagnosis of primary hyperparathyroidism. Primary hyperparathyroidism results from a parathyroid adenoma in the majority of cases and is detected by ultrasound during pregnancy. Primary hyperparathyroidism in pregnancy causes significant risks to both mother and fetus. The maternal complication rate is 14-67%, however, the most serious complication is hypercalcemic crisis, which requires increased surveillance in the postpartum period. Obstetrical complications are also induced by primary hyperparathyroidism, such as acute polyhydramnios, or intrauterine growth retardation. The fetal complication rate can reach 45-80% of cases with neonatal hypocalcemia as the main complication. If medical treatment is based on hyperhydration, only surgical treatment is curative.

CONCLUSION

Surgery should be proposed to symptomatic patients or those with high blood calcium levels, discussed in interdisciplinary committee and should be organized ideally in the second trimester to avoid maternal and fetal complications.

Expert consensus on multidisciplinary approach to the diagnosis and treatment of primary hyperparathyroidism in pregnancy in China

Primary hyperparathyroidism in pregnancy is a rare disease that can have detrimental effects on both maternal and fetal/neonatal outcomes. The physiological changes that occur during pregnancy can complicate the diagnosis, imaging examinations, and treatment of this disorder. To enhance our understanding and management of primary hyperparathyroidism in pregnancy, experts from various fields, including endocrinology, obstetrics, surgery, ultrasonography, nuclear medicine, pediatrics, nephrology, and general practice in China, collaborated to develop a consensus addressing the critical aspects of the diagnosis and treatment of primary hyperparathyroidism in pregnancy with a multidisciplinary team approach. This consensus provides valuable guidance for healthcare professionals in managing this condition, ultimately improving outcomes for both mothers and their babies.

Management of Hypoparathyroidism

Hypoparathyroidism (HypoPT) is a rare disorder characterized by hypocalcemia in the presence of a low or inappropriately normal parathyroid hormone level. HypoPT is most commonly seen after neck surgery, which accounts for approximately 75% of cases, whereas approximately 25% have HypoPT due to nonsurgical causes. In both groups of patients, conventional therapy includes calcium and active vitamin D analogue therapy aiming to maintain serum calcium concentration in the low normal or just below the normal reference range and normalize serum phosphorus, magnesium concentrations, and urine calcium levels. The limitations of conventional therapy include wide fluctuations in serum calcium, high pill burden, poor quality of life, and renal complications. Parathyroid hormone (PTH) replacement therapy may improve the biochemical profile in those in whom conventional therapy proves unsatisfactory. Based on a systematic review and meta-analysis of the literature, the panel made a graded recommendation suggesting conventional therapy as first line therapy rather than administration of PTH (weak recommendation, low quality evidence). When conventional therapy is deemed unsatisfactory, the panel considers use of PTH. Because pregnancy and lactation are associated with changes in calcium homeostasis, close monitoring is required during these periods with appropriate adjustment of calcium and active vitamin D analogue therapy to ensure that serum calcium remains in the mid to low normal reference range in order to avoid maternal and fetal complications. Emerging therapies include molecules with prolonged PTH action as well as different mechanisms of action that may significantly enhance drug efficacy and safety. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Evaluation and Management of Hypoparathyroidism Summary Statement and Guidelines from the Second International Workshop

This clinical practice guideline addresses the prevention, diagnosis, and management of hypoparathyroidism (HypoPT) and provides evidence-based recommendations. The HypoPT task forces included four teams with a total of 50 international experts including representatives from the sponsoring societies. A methodologist (GG) and his team supported the taskforces and conducted the systematic reviews. A formal process following the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology and the systematic reviews provided the structure for seven of the guideline recommendations. The task force used a less structured approach based on narrative reviews for 20 non-GRADEd recommendations. Clinicians may consider postsurgical HypoPT permanent if it persists for >12 months after surgery. To predict which patients will not develop permanent postsurgical HypoPT, we recommend evaluating serum PTH within 12 to 24 hours post total thyroidectomy (strong recommendation, moderate quality evidence). PTH > 10 pg/mL (1.05 pmol/L) virtually excludes long-term HypoPT. In individuals with nonsurgical HypoPT, genetic testing may be helpful in the presence of a positive family history of nonsurgical HypoPT, in the presence of syndromic features, or in individuals younger than 40 years. HypoPT can be associated with complications, including nephrocalcinosis, nephrolithiasis, renal insufficiency, cataracts, seizures, cardiac arrhythmias, ischemic heart disease, depression, and an increased risk of infection. Minimizing complications of HypoPT requires careful evaluation and close monitoring of laboratory indices. In patients with chronic HypoPT, the panel suggests conventional therapy with calcium and active vitamin D metabolites as first-line therapy (weak recommendation, low-quality evidence). When conventional therapy is deemed unsatisfactory, the panel considers the use of PTH. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Hypoparathyroidism: update of guidelines from the 2022 International Task Force

The 2022 International Task Force guidelines for chronic hypoparathyroidism will be published within several months in the Journal of Bone and Mineral Research. These guidelines update the original guidelines published in 2016, and include new information from literature published since then. Chronic postsurgical hypoparathyroidism is now defined as lasting for at least 12 months after surgery, rather than 6 months. Chronic postsurgical hypoparathyroidism may be predicted by serum PTH <10 pg/mL in the first 12-24 hours after surgery. The most common symptoms and complications of chronic hypoparathyroidism based on the literature are summarized in detail. How to monitor and manage patients with hypoparathyroidism is described in detail where recommendations can be given. These guidelines are intended to frame the diagnosis and care of patients with chronic hypoparathyroidism for at least the next five years.

Longitudinal Assessment of Calcium and Magnesium Levels in Women with Preeclampsia

The present study reports the levels of maternal serum calcium and magnesium from early pregnancy until delivery, along with cord levels, in women who developed preeclampsia (PE) and compares them with those without PE. A total of 324 pregnant women (216 non-PE and 108 PE women) were included in this retrospective case-control study of prospectively collected data nested in an observational cohort study. Maternal blood was collected at 4 time points during pregnancy (V1 = 11-14 weeks, V2 = 18-22 weeks, V3 = 26-28 weeks, and V4 = at delivery) and umbilical cord blood at delivery. Independent t tests were used to compare calcium, magnesium, and their ratio between two groups, and their associations with PE were studied using regression models. Calcium levels were similar between groups at all time points. Magnesium levels were lower (p = 0.021) at V2 in PE group as compared with non-PE group. Maternal calcium and magnesium levels were negatively associated, with blood pressure in early pregnancy. In fully adjusted logistic regression analysis, lower magnesium levels were associated with an increased risk of PE at V2 (OR 0.25 [95% CI 0.07, 0.94] p = 0.04). Lower magnesium in mid-pregnancy was associated with higher risk of PE. These changes were observed before the diagnosis of PE, thereby suggesting that they may have a role in the etiology of PE.

Hypercalcemia in Pregnancy

Hypercalcemic disorders are rare in pregnant women and are usually due to primary hyperparathyroidism. Clinical manifestations of hypercalcemia are nonspecific and can be masked by the physiologic changes of pregnancy. Furthermore, routine antenatal screening does not include serum calcium measurement and a hypercalcemia diagnosis may therefore be delayed until term or even after delivery. Timely recognition and appropriate interventions are essential to decrease maternal and fetal complications. Conservative measures are appropriate in the presence of mild hypercalcemia. Parathyroidectomy remains the mainstay of treatment for primary hyperparathyroidism with significant hypercalcemia not responding to conservative measures.

Bone metabolism in pregnancy and lactation

INTRODUCTION

Different hormonal mechanisms regulate bone metabolism during pregnancy and lactation. In both those periods of life, a fine modulation of calcium metabolism is necessary to meet the needs of foetus and newborn.

METHODS

We review scientific literature on the topic "osteoporosis", "pregnancy" and "lactation", evaluating the most relevant data from original articles, reviews and meta-analyses.

EVIDENCE SYNTHESIS

Pregnancy- and lactation-associated bone loss and related fractures rarely occur and, generally, clinicians have to manage it case to case, since there is not a unique guideline. Fortunately, bone mineral density (BMD) usually tends to recover within 12 months after weaning, thus, it could be reasonable waiting of assessing the effective magnitude of bone mass regain before starting any pharmacological treatment.

CONCLUSIONS

Osteoporosis and/or fragility fractures remain uncommon events associated with gestation and/or breastfeeding. The management of bone loss and/or fractures during those periods is generally conservative and a tailored approach is advisable in the absence of any specific recommendation in this field.

Maternal and fetal vitamin D and their roles in mineral homeostasis and fetal bone development

During pregnancy, female physiology adapts to meet the additional mineral demands of the developing fetus. Meanwhile, the fetus actively transports minerals across the placenta and maintains high circulating levels to mineralize the rapidly developing skeleton. Most of this mineral is accreted during the last trimester, including 30 g of calcium, 20 g of phosphate and 0.8 g of magnesium. Given the dependence of calcium homeostasis on vitamin D and calcitriol in the adult and child, it may be expected that vitamin D sufficiency would be even more critical during pregnancy and fetal development. However, the pregnant mother and fetus appear to meet their mineral needs independent of vitamin D. Adaptations in maternal mineral and bone metabolism during pregnancy appear to be invoked independent of maternal vitamin D, while fetal mineral metabolism and skeletal development appear to be protected from vitamin D deficiency and genetic disorders of vitamin D physiology. This review discusses key data from both animal models and human studies to address our current knowledge on the role of vitamin D and calcitriol during pregnancy and fetal development.

Association between ionised calcium and severity of postpartum haemorrhage: a retrospective cohort study

BACKGROUND

Postpartum haemorrhage (PPH) is often complicated by impaired coagulation. We aimed to determine whether the level of ionised calcium (Ca²⁺), an essential coagulation co-factor, at diagnosis of PPH is associated with bleeding severity.

METHODS

This was a retrospective cohort study of women diagnosed with PPH during vaginal delivery between January 2009 and April 2020. Ca²⁺ levels at PPH diagnosis were compared between women who progressed to severe PPH (primary outcome) and those with less severe bleeding. Severe PPH was defined by transfusion of ≥2 blood units, arterial embolisation or emergency surgery, admission to ICU, or death. Associations between other variables (e.g. fibrinogen concentration) and bleeding severity were also assessed.

RESULTS

For 436 patients included in the analysis, hypocalcaemia was more common among patients with severe PPH (51.5% vs 10.6%, P<0.001). In a multivariable logistic regression model, Ca²⁺ and fibrinogen were the only parameters independently associated with PPH severity with odds ratios of 1.14 for each 10 mg dl^-1 decrease in fibrinogen (95% confidence interval [CI], 1.05-1.24; P=0.002) and 1.97 for each 0.1 mmol L^-1 decrease in Ca²⁺ (95% CI, 1.25-3.1; P=0.003). The performance of Ca²⁺ or fibrinogen was not significantly different (area under the curve [AUC]=0.79 [95% CI, 0.75-0.83] vs AUC=0.86 [95% CI, 0.82-0.9]; P=0.09). The addition of Ca²⁺ to fibrinogen improved the model, leading to AUC of 0.9 (95% CI, 0.86-0.93), P=0.03.

CONCLUSIONS

Ca²⁺ level at the time of diagnosis of PPH was associated with risk of severe bleeding. Ca²⁺ monitoring may facilitate identification and treatment of high-risk patients.

Right ectopic paraesophageal parathyroid adenoma with refractory hypercalcemia in pregnancy: A case report and review of the literature

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Ectopic parathyroid adenoma (EPA) is rare during pregnancy but poses multiple challenges in diagnosis and treatment.

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EPA presents with refractory hypercalcemia which leads to symptoms and complications in the mother and fetus.

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Preoperative localization of EPA is important and allows for a focused surgical procedure.

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Surgery is a definitive treatment and can safely be performed during the 2nd trimester of pregnancy.

Introduction

Ectopic parathyroid adenoma is rare during pregnancy but poses multiple challenges in treatment. It presents as primary hyperparathyroidism which leads to symptoms and complications of hypercalcemia in both the mother and fetus.

Presentation of case

A 38-year-old Sudanese female presented with diffuse bone pain and polyuria. Laboratory investigations revealed elevated serum calcium and parathyroid hormone. Ultrasound of the neck did not show any abnormal lesion, however 99mTc-sestamibi scan showed a right sided parathyroid adenoma, and an earlier CT scan showed the adenoma to be in an ectopic paraesophageal position. Focused surgical neck exploration was done, and the ectopic parathyroid adenoma was excised.

Discussion

Preoperative localization of the ectopic parathyroid adenoma allows for a focused surgical procedure. Ultrasound is the safest during pregnancy, but 99mTc-sestamibi and CT scan may be necessary if ultrasound or initial bilateral neck exploration do not detect any adenoma. Mild elevations in maternal serum calcium can have detrimental effects on the fetus which suggests that a surgical approach may be necessary in the majority of cases.

Conclusions

Ectopic parathyroid adenoma is rare during pregnancy and is detrimental to both the mother and fetus. Preoperative localization allows for a focused surgery which is a definitive treatment and can safely be performed during the 2nd trimester of pregnancy.

Parathyroid Diseases

Although uncommon in pregnancy, parathyroid dysfunction may produce significant perinatal and maternal morbidity and mortality. The prevalence of hyperparathyroidism is 0.5%. The most common cause of primary hyperparathyroidism in pregnancy is a single parathyroid adenoma, which is present in nearly 80% of cases. Surgery is the only definitive treatment for primary hyperparathyroidism, with a cure rate that is excellent. The most common etiology of hypoparathyroidism is damage to the parathyroid glands after surgery, with an incidence of 0.2%. Treatment of hypoparathyroidism is usually a high-calcium diet with vitamin D supplementation. Vitamin D deficiency is common, associated with perinatal morbidity and easily corrected.

Standards of care for hypoparathyroidism in adults: a Canadian and International Consensus

PURPOSE

To provide practice recommendations for the diagnosis and management of hypoparathyroidism in adults.

METHODS

Key questions pertaining to the diagnosis and management of hypoparathyroidism were addressed following a literature review. We searched PubMed, MEDLINE, EMBASE and Cochrane databases from January 2000 to March 2018 using keywords 'hypoparathyroidism, diagnosis, treatment, calcium, PTH, calcidiol, calcitriol, hydrochlorothiazide and pregnancy'. Only English language papers involving humans were included. We excluded letters, reviews and editorials. The quality of evidence was evaluated based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. These standards of care for hypoparathyroidism have been endorsed by the Canadian Society of Endocrinology and Metabolism.

RESULTS

Hypoparathyroidism is a rare disease characterized by hypocalcemia, hyperphosphatemia and a low or inappropriately normal serum parathyroid hormone level (PTH). The majority of cases are post-surgical (75%) with nonsurgical causes accounting for the remaining 25% of cases. A careful review is required to determine the etiology of the hypoparathyroidism in individuals with nonsurgical disease. Hypoparathyroidism is associated with significant morbidity and poor quality of life. Treatment requires close monitoring as well as patient education. Conventional therapy with calcium supplements and active vitamin D analogs is effective in improving serum calcium as well as in controlling the symptoms of hypocalcemia. PTH replacement is of value in lowering the doses of calcium and active vitamin D analogs required and may be of value in lowering long-term complications of hypoparathyroidism. This manuscript addresses acute and chronic management of hypoparathyroidism in adults.

MAIN CONCLUSIONS

Hypoparathyroidism requires careful evaluation and pharmacologic intervention in order to improve serum calcium and control the symptoms of hypocalcemia. Frequent laboratory monitoring of the biochemical profile and patient education is essential to achieving optimal control of serum calcium.

A Case of Pregnancy Complicated by Primary Hyperparathyroidism Due to a Parathyroid Adenoma

BACKGROUND Primary hyperparathyroidism is most common in women during the menopause and its occurrence in pregnant women is rare. However, because neonatal mortality is associated with maternal hyperparathyroidism, early diagnosis is essential. This report describes the case of a late diagnosis of primary hyperparathyroidism in a 28-year-old pregnant woman and describes the effects on the mother and neonate. CASE REPORT During her second pregnancy, a 28-year-old woman presented with symptoms of general weakness, bone and joint pain, multiple fractures with bone deformity, muscle weakness, and gait disturbance. Due to the high risk of perinatal pathology, a cesarean section was performed. Several weeks later, she underwent thoracoscopic removal of an ectopic parathyroid gland located at the aortic arch. Hypocalcemia in the newborn infant required treatment with calcium and magnesium supplements. CONCLUSIONS This case demonstrates that primary hyperparathyroidism during pregnancy requires timely diagnosis and treatment to reduce potential maternal and fetal complications. Screening for primary hyperparathyroidism should be undertaken in pregnant women with any symptoms associated with hypercalcemia. Treatment should be individualized and includes conservative management, parathyroidectomy in the second trimester, or parathyroidectomy performed in the early postpartum period.

Serum Calcium and Magnesium Levels in Normal Ghanaian Pregnant Women: A Comparative Cross-Sectional Study

BACKGROUND:

Pregnancy is described as a normal physiologic state associated with various biochemical changes. Magnesium and calcium are essential macronutrients required for foetal growth. Complications associated with their deficiency during normal pregnancy include; low neonatal birth weight, pre-eclampsia, eclampsia and preterm labour. Changes in serum levels of magnesium and calcium in normal pregnancy have not been extensively studied among Ghanaian women.

AIM:

To determine the variation in serum magnesium and calcium levels with gestational age in normal pregnancy in Ghanaian women.

METHODS:

A hospital-based comparative cross-sectional study was conducted among 32 normal non-pregnant women (Group A) and 100 normal pregnant women (Group B) attending the clinic at the Korle-Bu Teaching hospital. The group B pregnant women were further divided into Group B1 (n = 33), Group B2 (n = 37) and Group B3 (n = 30) based on their pregnancy gestation as first, second and third trimester respectively. Blood samples were obtained from the antecubital vein of subjects and total serum calcium, magnesium, protein and albumin were estimated. Data obtained were analysed using SPSS for windows version 20. Analysis of variance (ANOVA) was employed to determine the statistical differences between the groups. A p-value of ≤ 0.05 was considered significant.

RESULTS:

Mean serum total calcium and magnesium in first, second and third trimester normal pregnant women were 2.14 ± 0.16, 2.13 ± 0.44, 2.13 ± 0.35 mmol/L and 0.77 ± 0.11, 0.77 ± 0.16 and 0.76 ± 0.14 mmol/L respectively. Mean serum total calcium and magnesium levels in non-pregnant women were 2.20 ± 0.16 and 0.80 ± 0.10 mmol/L respectively. There was a statistically non-significant difference in serum total calcium and magnesium between non-pregnant and normal pregnant women, with p-values of 0.779 and 0.566 respectively. Mean total serum protein and albumin in first, second and third-trimester normal pregnant women were 68.42 ± 10.37, 70.46 ± 6.84, 66.70 ± 7.83 g/L and 39.92 ± 3.22, 40.75 ± 8.06, 38.26 ± 3.02 g/L respectively. Mean total serum protein and albumin in non-pregnant women were 73.13 ± 7.02 and 42.94 ± 3.03 g/L respectively. Mean total serum protein and albumin levels were lower in pregnant women as compared to non-pregnant women with the difference being significant in the third trimester (p-values of 0.012 and 0.002).

CONCLUSION:

Total serum calcium and magnesium levels in normal pregnancy were non-significantly lower compared to non-pregnant women in Ghana. There was a reduction in total serum protein, and albumin levels during pregnancy with a significant reduction noticed during the third trimester compared to the non-pregnant state.

Development of Parafollicular Cells and their Relationship with Developing Thyroid Follicles in Human Foetuses

INTRODUCTION

The parafollicular cells or clear (C) cells in man are part of neuroendocrine system under Amine Precursor Uptake and Decarboxylation (APUD) cells. Their role in adults has been reputable but in foetus is still unclear.

AIM

The present study was a baseline study endeavouring to describe the chronological development of the parafollicular cells with particular focus on its correlation with developing human thyroid follicles.

MATERIALS AND METHODS

The study was conducted on 10 aborted foetuses (14-28 weeks), procured from the Department of Obstetrics and Gynaecology, Lok Nayak Hospital, New Delhi, India. Serial sections of foetal thyroid gland were generated, stained with haematoxylin and eosin, and immunohistochemistry using the anticalcitonin antibody and examined qualitatively.

RESULTS

In our study, the parafollicular cells were seen as earlier as by 14^th week. They became morphologically and functionally mature by 16^th week of gestation. The parafollicular cells were getting organized from scattering to parafollicular location then to a more localized area, i.e., intrafollicular along with the follicular development. As the follicles were enlarging, the intrafollicularly located parafollicular cells which was initially present in groups was getting displaced singly between the follicular cells in the same follicle.

CONCLUSION

The sequential development pattern of the parafollicular cells in relation to developing thyroid follicles was established. This immunohistochemical study also concluded that the parafollicular cells might have higher character to play in the early gestational age such as regulation of ossification in the human foetus.

A study of bone turnover markers in gestational diabetes mellitus

INTRODUCTION

Gestational diabetes is defined as carbohydrate intolerance resulting in hyperglycemia of variable severity with the first recognition during pregnancy. Established risk factors for gestational diabetes mellitus (GDM) are maternal age, obesity, family history of diabetes, etc. Vitamin D, parathyroid hormone (PTH), and various other hormones are known for their function in maintaining calcium and phosphorous homeostatic. Furthermore, Vitamin D, PTH serum ionized calcium, and alkaline phosphatase (ALP) have been reported to be altered with glucose homeostasis. The present study compares the bone markers in pregnant women with and without gestational diabetes.

MATERIALS AND METHODS

This cross-sectional study was conducted at outpatient antenatal check-up clinic and outpatient diabetic clinics at J. N. Medical College and Hospital, Aligarh. One hundred pregnant females, of which fifty with GDM and fifty without GDM, were included in the study from January 2014 to November 2015. Detailed history, physical examination, and anthropometric measurement were done. Bone turnover markers in the form of Vitamin D, parathyroid hormone, serum ionized calcium, and serum ALP were measured in pregnant women who had gestational diabetes which was compared with normal pregnant women.

RESULTS

In our study, the mean age of participate of GDM group was 28.2 ± 3 years, while the mean age group in non-GDM group was 25.44 ± 2.78 years. Ionized calcium in GDM was found to be 4.606 ± 0.354 mEq/L, while in non-GDM, it was 4.548 ± 0.384 mEq/L, P = 0.430. Vitamin D came out to be 21.80 ± 9.48 ng/ml, while it was 32.346 ± 8.37 ng/ml in non-GDM group. Serum PTH in GDM group was 71.436 ± 36.189 pg/ml and 37.168 ± 8.128 pg/ml in nondiabetic gestational group. Serum ALP in GDM group was 9.1 ± 4.56 KA U/dl and 6.98 ± 2.2 KA U/dl in nondiabetic gestational group, P - 0.0038. In GDM group, there was a significant negative linear correlation between PTH and 25-hydroxyvitamin D with research correlation coefficient r = -0.9073, P = 0; there was a significant positive linear correlation coefficient between PTH and ALP with Persian correlation coefficient r = 0.6597, P = 0; there was no statistically significant correlation between PTH and ionized calcium r = 0.1416, P = 0.3267.

CONCLUSION

All GDM subjects should ideally be screened for serum calcium, vitamin D, PTH, ALP. If found impaired should immediately be corrected in order to prevent its adverse effects on maternal and fetal outcome. Vitamin D supplementation should ideally be initiated in all GDM females even if the above parameters are not investigated in Indian setup.

Maternal vitamin D levels during pregnancy and neonatal health: evidence to date and clinical implications

Low maternal vitamin D levels during pregnancy have been associated with a plethora of adverse neonatal outcomes, including small for gestational age and preterm births, detrimental effect on offspring bone and teeth development, and risk of infectious diseases. Although most observational studies indicate a significant linear relationship between maternal 25-hydroxyvitamin D and the above outcomes, some randomized controlled trials to date are inconclusive, mostly due to differences in study design and supplementation regimen. The currently available results indicate that vitamin D supplementation during pregnancy reduces the risk of preterm birth, low birth weight, dental caries of infancy, and neonatal infectious diseases such as respiratory infections and sepsis. This narrative review aims to summarize available trial results regarding the effect of low maternal vitamin D levels during pregnancy, in conjunction with neonatal outcomes on the field, with a discourse on the appropriate clinical approach of this important issue.

Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery

During pregnancy and lactation, female physiology adapts to meet the added nutritional demands of fetuses and neonates. An average full-term fetus contains ∼30 g calcium, 20 g phosphorus, and 0.8 g magnesium. About 80% of mineral is accreted during the third trimester; calcium transfers at 300-350 mg/day during the final 6 wk. The neonate requires 200 mg calcium daily from milk during the first 6 mo, and 120 mg calcium from milk during the second 6 mo (additional calcium comes from solid foods). Calcium transfers can be more than double and triple these values, respectively, in women who nurse twins and triplets. About 25% of dietary calcium is normally absorbed in healthy adults. Average maternal calcium intakes in American and Canadian women are insufficient to meet the fetal and neonatal calcium requirements if normal efficiency of intestinal calcium absorption is relied upon. However, several adaptations are invoked to meet the fetal and neonatal demands for mineral without requiring increased intakes by the mother. During pregnancy the efficiency of intestinal calcium absorption doubles, whereas during lactation the maternal skeleton is resorbed to provide calcium for milk. This review addresses our current knowledge regarding maternal adaptations in mineral and skeletal homeostasis that occur during pregnancy, lactation, and post-weaning recovery. Also considered are the impacts that these adaptations have on biochemical and hormonal parameters of mineral homeostasis, the consequences for long-term skeletal health, and the presentation and management of disorders of mineral and bone metabolism.

Association Between Recurrence of Urinary Calculi and Childbirth: A Population-Based Case-Control Study

We examined the recurrence rate of urinary calculi (UC) in women after childbirth. The recurrence of UC is common, but no previous studies mentioned the risk of recurrence after childbirth. We performed a nationwide population-based cohort study to investigate whether childbirth could correlate with the recurrence of UC by using data from the National Health Insurance Research Database in Taiwan. Nulliparous women (age ≥20 years) receiving a diagnosis of first episode of UC between 2000 and 2002 were enrolled. We recorded the events of recurrence between parous patients (n = 737) and matched-control nulliparous patients (n = 737). The average ages for parous patients and controls were 27.41 and 27.54, respectively. The recurrence rate was 11.67% (86 of 737) in the childbirth cohort group and 21.57% (159 of 737) in the nonchildbirth cohort group. The childbirth cohort group was associated with a significantly decreased risk of secondary UC (adjusted hazard ratio, 0.45; 95% confidence interval, 0.35–0.59) compared with those who did not deliver a child. This relationship should be studied further.

Novel anatomic adaptation of cortical bone to meet increased mineral demands of reproduction

The goal of this study was to investigate the effects of reproductive adaptations to mineral homeostasis on the skeleton in a mouse model of compromised mineral homeostasis compared to adaptations in control, unaffected mice. During pregnancy, maternal adaptations to high mineral demand include more than doubling intestinal calcium absorption by increasing calcitriol production. However, calcitriol biosynthesis is impaired in HYP mice, a murine model of X-linked hypophosphatemia (XLH). In addition, there is a paucity of mineralized trabecular bone, a primary target of bone resorption during pregnancy and lactation. Because the highest density of mineral is in mature cortical bone, we hypothesized that mineral demand is met by utilizing intracortical mineral reserves. Indeed, analysis of HYP mice revealed dramatic increases in intracortical porosity characterized by elevated serum PTH and type-I collagen matrix-degrading enzyme MMP-13. We discovered an increase in carbonate ion substitution in the bone mineral matrix during pregnancy and lactation of HYP mice, suggesting an alternative mechanism of bone remodeling that maintains maternal bone mass during periods of high mineral demand. This phenomenon is not restricted to XLH, as increased carbonate in the mineral matrix also occurred in wild-type mice during lactation. Taken together, these data suggest that increased intracortical perilacunar mineral turnover also contributes to maintaining phosphate levels during periods of high mineral demand. Understanding the mechanisms of skeletal contribution to mineral homeostasis is important to improving the treatment and prevention of fracture risk and bone fragility for female patients with XLH, but also provides important insight into the role and unique adaptations of the maternal skeleton to the demands of fetal development and the needs of postnatal nutrition.

Hypoparathyroidism in pregnancy

Hypoparathyroidism is an uncommon endocrine deficiency characterised by low serum calcium, absent or inappropriately low parathyroid hormone and normal or high serum phosphorus levels. Parathyroid hormone is essential for calcium homoeostasis. Pregnancy and lactation are known for increased calcium requirement. They cause calcium stress as well as alter its metabolism. Hence, many abnormalities are expected in hypoparathyroidism during pregnancy and lactation. We report a case of pregnancy in postsurgical hypoparathyroidism, which is rarely encountered in antenatal clinics. We describe our clinical, biochemical and therapeutic experience of pregnancy and lactation in this patient with hypoparathyroidism.

Regulation of calcitriol biosynthesis and activity: focus on gestational vitamin D deficiency and adverse pregnancy outcomes

Vitamin D has garnered a great deal of attention in recent years due to a global prevalence of vitamin D deficiency associated with an increased risk of a variety of human diseases. Specifically, hypovitaminosis D in pregnant women is highly common and has important implications for the mother and lifelong health of the child, since it has been linked to maternal and child infections, small-for-gestational age, preterm delivery, preeclampsia, gestational diabetes, as well as imprinting on the infant for life chronic diseases. Therefore, factors that regulate vitamin D metabolism are of main importance, especially during pregnancy. The hormonal form and most active metabolite of vitamin D is calcitriol. This hormone mediates its biological effects through a specific nuclear receptor, which is found in many tissues including the placenta. Calcitriol synthesis and degradation depend on the expression and activity of CYP27B1 and CYP24A1 cytochromes, respectively, for which regulation is tissue specific. Among the factors that modify these cytochromes expression and/or activity are calcitriol itself, parathyroid hormone, fibroblast growth factor 23, cytokines, calcium and phosphate. This review provides a current overview on the regulation of vitamin D metabolism, focusing on vitamin D deficiency during gestation and its impact on pregnancy outcomes.

Primary hyperparathyroidism during pregnancy

PURPOSE

Primary hyperparathyroidism (pHPT) during pregnancy is rare and associated with increased morbidity and mortality for both mother and fetus. This review aims to draw together recent thinking on pregnancy and pHPT.

METHODS

We have performed a Pubmed (Medline(®)) search with no time limit using "primary hyperparathyroidism", "pregnancy" or "management" as keywords. We reviewed 37 articles in English and French languages on pHPT characteristics, clinical presentations, pregnancy complications, birth outcomes and management of pHPT during pregnancy.

RESULTS

The diagnosis of pHPT is characterized by an elevated serum calcium level associated with an inappropriate increase in the parathyroid hormone level. The clinical manifestations are directly related to the calcium level. Usual techniques to detect parathyroid adenoma or hyperplasia, as computerized tomography and 99mTc-sestamibi scintigraphy, are not recommended in pregnancy. Thus, ultrasonography of the neck is the current first-line investigation during pregnancy for localization of parathyroid diseases. pHPT during pregnancy with mildly elevated calcium levels may be managed with medical treatment: intravenous or oral rehydratation, with or without forced diuresis. Few drugs are available for pHTP during pregnancy; calcitonin and cinacalcet require further study; bisphosphonate should be restricted to life-threatening hypercalcemia. Surgery is the only curative treatment and is recommended when calcium levels are above 2.75 mmol/L. It should be performed in the second trimester and considered in the third trimester if there is inadequate response to medical therapy.

CONCLUSION

Early diagnosis of pHPT in a pregnant woman, followed by appropriate management and treatment, has been shown to significantly reduce maternal and fetal complications.

Effect of magnesium therapy on nocturnal leg cramps: a systematic review of randomized controlled trials with meta-analysis using simulations

BACKGROUND AND OBJECTIVE

Nocturnal leg cramps (NLC) are common in primary care and may cause severe pain and sleep disturbance. We systematically reviewed the effectiveness of magnesium in treating NLC and the side-effect profile of magnesium compared to placebo.

METHODS

We searched Medline, Embase, Cochrane Library, ClinicalTrials.gov, the International Standard Randomised Controlled Trial Number and the International Clinical Trials Registry Platform registries until August 2012. All randomized controlled trials (RCTs) comparing magnesium therapy for NLC in adults with any other comparator were eligible. Two investigators independently selected, extracted data from and rated the risk of bias of relevant studies. To compensate for the heterogeneity in outcome measures, simulations were used to summarize the data.

RESULTS

Seven RCTs were included in the review (n = 361), all comparing magnesium to placebo. Three of these trials included only pregnant women. The difference in the median number of leg cramps per week between the placebo and the intervention groups was 0.345 (quantile 2.5%: -0.133, quantile 97.5%: 0.875). This difference was 0.807 (quantile 2.5%: 0.015, quantile 97.5%: 1.207) in the three studies involving only pregnant women and 0.362 (quantile 2.5%: -0.386, quantile 97.5%: 1.148) in the others. Overall gastrointestinal side effects were slightly more common with magnesium therapy than with placebo. The strength of this evidence was weak, mainly due to small study sizes and short follow-up.

CONCLUSIONS

Magnesium therapy does not appear to be effective in the treatment of NLC in the general population, but may have a small effect in pregnant women. Further research using better designed RCTs is necessary.

Parathyroid and calcium metabolism disorders during pregnancy

Parathyroid disorders are not common among pregnant women, but harbor a significant morbidity and mortality potential if they remain unrecognized and untreated. The symptoms caused by abnormally low or high blood free calcium level are mostly non-specific in the initial stages, thus when recognized might pose a real danger. Here we will survey the alterations in calcium metabolism induced by pregnancy, and describe the clinical manifestations, diagnosis and treatment of parathyroid and other calcium metabolism disorders during pregnancy. The current literature on the impact of calcium and vitamin D deficiency during pregnancy will also be reviewed.

Calcium economy in human pregnancy and lactation

Pregnancy and lactation are times of additional demand for Ca. Ca is transferred across the placenta for fetal skeletal mineralisation, and supplied to the mammary gland for secretion into breast milk. In theory, these additional maternal requirements could be met through mobilisation of Ca from the skeleton, increased intestinal Ca absorption efficiency, enhanced renal Ca retention or greater dietary Ca intake. The extent to which any or all of these apply, the underpinning biological mechanisms and the possible consequences for maternal and infant bone health in the short and long term are the focus of the present review. The complexities in the methodological aspects of interpreting the literature in this area are highlighted and the inter-individual variation in the response to pregnancy and lactation is reviewed. In summary, human pregnancy and lactation are associated with changes in Ca and bone metabolism that support the transfer of Ca between mother and child. The changes generally appear to be independent of maternal Ca supply in populations where Ca intakes are close to current recommendations. Evidence suggests that the processes are physiological in humans and that they provide sufficient Ca for fetal growth and breast-milk production, without relying on an increase in dietary Ca intake or compromising long-term maternal bone health. Further research is needed to determine the limitations of the maternal response to the Ca demands of pregnancy and lactation, especially among mothers with marginal and low dietary Ca intake, and to define vitamin D adequacy for reproductive women.

Extrarenal expression of the 25-hydroxyvitamin D-1-hydroxylase

Like the vitamin D receptor (VDR), the CYP27B1-hydroxylase is expressed widely in human tissues. This expression profile establishes the potential for interaction of the VDR with the product of the CYP27B1, 1,25-dihydroxyvitamin D (1,25-(OH)(2)D), in either an intracrine or paracrine mode. This expansive expression profile also suggests that the local production and action of 1,25-(OH)(2)D to regulate VDR-directed gene expression may be similarly wide-ranging and distinct from what occurs in the kidney; the proximal renal tubular epithelial cell is the richest source of the CYP27B1 and the site for production of 1,25-(OH)(2)D destined to function as a hormone. Existence of the CYP27B1 at extrarenal sites has been widely documented, although the functional impact of the enzyme in these tissues has yet to be fully demonstrated. Two notable exceptions are the disease-activated macrophage (e.g., in sarcoidosis or tuberculosis) and the placenta. These two tissues are capable of generating enough 1,25-(OH)(2)D so as to be detectable in the general circulation. As such, this review will focus on CYP27B1 expression only at these two sites, theorizing that 1,25-(OH)(2)D production at these sites is for the purpose of local immunoregulatory function, not for controlling calcium balance in the host or the fetus.

Vitamin D, the placenta and pregnancy

Impaired vitamin D status is common to many populations around the world. However, data suggest that this is a particular problem for specific groups such as pregnant women. This has raised important questions concerning the physiological and clinical impact of low vitamin D levels during pregnancy, with implications for classical skeletal functions of vitamin D, as well as its diverse non-classical actions. The current review will discuss this with specific emphasis on the classical calciotropic effects of vitamin D as well as the less well established immunological functions of vitamin D that may influence pregnancy outcome. The review also describes the pathways that are required for metabolism and function of vitamin D, and the various clinical complications that have been linked to impaired vitamin D status during pregnancy.

Calcium and bone metabolism disorders during pregnancy and lactation

Pregnancy and lactation cause a substantial increase in demand for calcium that is met by different maternal adaptations within each period. Intestinal calcium absorption more than doubles during pregnancy, whereas the maternal skeleton resorbs to provide most of the calcium content of breast milk during lactation. These maternal adaptations also affect the presentation, diagnosis, and management of disorders of calcium and bone metabolism. Although some women may experience fragility fractures as a consequence of pregnancy or lactation, for most women, parity and lactation do not affect the long-term risks of low bone density, osteoporosis, or fracture.

Primary hyperparathyroidism in pregnancy-a rare cause of life-threatening hypercalcemia: case report and literature review

Objective. To report a case of primary hyperparathyroidism in a pregnant patient, report the obstetric and neonatal outcomes, and review the relevant literature. Results. A 29-year-old primigravida was successfully treated for PHP with minimally invasive resection of a parathyroid adenoma in the second trimester of pregnancy. A healthy baby girl was delivered at 37-week gestation with an unremarkable neonatal course. To the best of our knowledge, this is the second case report in the literature utilizing intraoperative PTH during a parathyroidectomy in a pregnant woman. Conclusions. Primary hyperparathyroidism is a rare life-threatening condition that can present during pregnancy. The diagnosis can be difficult to establish during pregnancy, given the nonspecific symptoms related to hypercalcemia. However, a better understanding of the condition, improved diagnostic studies, and well-organized multidisciplinary management decisions can significantly reduce the morbidity and mortality associated with the disease during pregnancy. This case report is presented to highlight the value of early diagnosis and appropriate management of PHP during pregnancy.

VITAMIN D AND HUMAN PREGNANCY

At the end of 2007, Time magazine listed the “benefits of vitamin D” as one of its top 10 medical breakthroughs for that year. Since then there has been a remarkable upsurge of interest in vitamin D, with new research advances seemingly published on a weekly basis. In particular, there has been increasing awareness of the variability of vitamin D status in populations across the globe and, significantly, a growing debate about the need for revised parameters for vitamin D supplementation. Although sub-optimal vitamin D is likely to be a widespread problem for 21stcentury societies, it is also clear that some groups are at much greater risk of low vitamin D status. Prominent amongst these are pregnant women and the aim of the following review article will be to discuss this problem in further detail with specific emphasis on its potential physiological and clinical impact.

Blood copper, zinc, calcium, and magnesium levels during different duration of pregnancy in Chinese

Concentrations of various trace elements are altered during pregnancy with changes in the mother's physiology and the requirements of growing fetus. The aim of the present longitudinal study was to learn the changes of trace element copper (Cu), zinc (Zn), calcium (Ca), and magnesium (Mg) of normal pregnant woman during different durations of pregnancy and establish the reference values of changes of statistical significance. Blood samples were obtained from 128 normal pregnant women during early (10-14th week), mid (20-24th week), and late (30-34th week) pregnancy and 6-12th week postpartum and 120 healthy unpregnant healthy women. The full blood concentrations of chosen elements were measured by means of an atomic absorption spectrophotometer. Changes on levels of Cu, Ca, and Mg during all the three durations of pregnancy and Zn during mid and late pregnancy and postpartum were of statistical significance and new reference values of them were set in the present study. These new reference values will be helpful in assessing the health status of pregnant women with a socioeconomic and racial background similar to those of our study participants and give treatments to them promptly.

The Role of Calcium Correction during Normal Pregnancy at Third Trimester in Mosul

OBJECTIVES

To assess calcium status in healthy pregnant women during limited sun exposure time in winter, and to demonstrate the possible effect of serum albumin alterations on serum total calcium level and the role of albumin adjusted calcium concentration.

METHODS

Subjects enrolled in the study included 160 apparently healthy women divided equally into four groups (I - IV), group I was considered as the control group, composed of non-pregnant women. Groups II-IV were composed of pregnant women in the first, second and third trimesters respectively. Semiquantitative urine protein determination and measurement of serum total calcium, ionized calcium, albumin, phosphorous and creatinine with calculation of corrected calcium were performed in all groups. The results were statistically evaluated by standard statistical methods.

RESULTS

There was no significant difference in serum ionized calcium, corrected calcium and phosphorous during pregnancy. However, there was a significant reduction of serum total calcium, albumin and creatinine in pregnant women at second and third trimesters. In each group, a significant positive correlation was observed between total calcium with corrected and ionized calcium.

CONCLUSION

In healthy pregnant women even during limited sun exposure time in winter, there was no need for calcium supplementation in spite of the continuous and progressive reduction of serum measured total calcium during the second and third trimesters due to dilutional hypoalbuminemia. During pregnancy, measured calcium is parallel to both corrected and ionized calcium and since there was no significant difference between measured and corrected calcium, therefore, measured calcium is a useful test in assessing calcium status and suggests the need to establish a reference range for pregnant women.

Calcium in midpregnancy

OBJECTIVE

To establish reference value for serum calcium concentration and urinary calcium excretion during mid pregnancy and to find out variation of calcium intake in pregnant women.

MATERIALS AND METHODS

This was a cross sectional study conducted in antenatal clinic of department of Obstetrics and Gynaecology. A total of 543 pregnant women with pregnancy period of second trimester were enrolled for the study. Eligible healthy, vegetarian primigravid women provided serum and 24 h urinary samples for determination of serum calcium and urinary calcium excretion. Dietary intake calculated by 3-day recall method. Variation of calcium intake according to various demographic characteristics was noted.

RESULTS

Statistical analysis done with SPSS software. The mean total serum calcium and 24 h urinary calcium and dietary intake of calcium were 8.1+/-1.5 mg/dl (5.1-11.9), 129.56+/-67.08 mg (40.5-400) and 324.37+/-199.47 mg/day (85.71-910.71) respectively. The 95th percentiles for serum calcium were 10.56 mg/dl and urinary calcium excretion was 280.70 mg/24 h. Educational level, monthly income and height were positive correlated with calcium intake.

CONCLUSION

This preliminary study defines the first standard value for calcium status in pregnant second trimester females of northern India. Calcium intake in pregnant females is affected by various demographic characteristics. There is need to change dietary pattern by improving education and socio-economic level.

Does oral magnesium substitution relieve pregnancy-induced leg cramps?

OBJECTIVE

Our aim was to assess the effect of 360mg magnesium oral substitution daily among pregnant women suffering from leg cramps in pregnancy, defined as painful cramps different from restless legs symptoms.

STUDY DESIGN

In a double blind randomised controlled trial healthy pregnant women between 18 and 36 weeks of pregnancy suffering from painful leg cramps, at least twice a week, were invited to participate. Forty-five women were enrolled initially, 38 completed the treatment and were treated during 2 weeks with either magnesium (360mg=15mmol magnesium lactate and magnesium citrate, Nycoplus Magnesium), or placebo tablets. Serum magnesium and calcium were investigated together with urine magnesium and magnesium-creatinin ratio on day 1 and day 15. Frequency and intensity of leg cramps were recorded. The study was powered to detect a 50% reduction in leg cramps.

RESULTS

Registration of pain frequency and intensity during the two study weeks demonstrated no significant differences between the two groups. Mean number and intensity of cramps were 9.5 (S.D. 5.1) and 13.2 (S.D. 6.5) in the magnesium group, compared to 7.7 (S.D. 4.7) and 11.4 (S.D. 8.5) in the placebo group. Baseline magnesium levels were 0.77 and 0.74mmol/L in the magnesium group and the placebo group, respectively No significant differences between the two groups, or within the groups, were found when comparing serum values of serum magnesium and total calcium at inclusion time and at the end of the treatment. There was a statistically significant increase in magnesium excretion in the magnesium treatment group (p<0.01). The number of dropouts was two in the treatment group and five in the control group.

CONCLUSIONS

No significant effect on frequency or intensity of leg cramps in pregnant women of magnesium treatment with 360mg daily could be detected in this trial.

Expression of prolactin receptor and prolactin in normal and malignant thyroid: a tissue microarray study

OBJECTIVE

There is increasing evidence involving prolactin (PRL) and its receptor (PRLR) in the development of different cancers. The aim of the present study was to investigate the expression of PRLR and PRL in human thyroid tissues.

DESIGN AND METHODS

Using tissue microarray (TMA) by immunohistochemical staining, we examined the expression level of PRLR and PRL in 314 specimens from 71 thyroid cancer patients and 15 normal thyroid samples.

RESULTS

Expression of the PRLR was observed in 93.3% of normal thyroid samples and in 76.1% of all thyroid cancers, while expression of PRL was observed in only 10% of medullary thyroid carcinomas and not at all in the other specimens, whether normal or neoplastic. Moreover, results suggested an overexpression of PRLR in 70% of medullary thyroid carcinomas, whereas 53.3% of poorly differentiated thyroid carcinomas showed a negative pattern of staining (p = 0.014 vs normal).

CONCLUSIONS

Present data revealed, for the first time, a widespread expression of PRLR in normal and neoplastic human thyroid tissues as well as a scarce expression of PRL, observed only in a few medullary thyroid carcinomas. Whether the overexpression of PRLR observed in medullary thyroid carcinomas or the underexpression of PRLR observed in poorly differentiated thyroid carcinomas play a contributory role in the oncogenesis of these tumors remains to be determined.

Calcium and bone metabolism during pregnancy and lactation

Pregnancy and lactation both place significant demands on the mother to provide sufficient calcium (among other minerals and nutrients) to the fetus and neonate. Despite facing similar demands for calcium during pregnancy and lactation, the maternal adaptations differ significantly between these two reproductive periods. Women lose 300 to 400 mg of calcium daily through breast milk, and this calcium demand is met by a 5-10% loss of skeletal mineral content during 6 months of exclusive lactation. Most importantly, the lost mineral is fully restored within a few months of weaning, such that women who have breastfed do not have a long-term deficit in skeletal mineral content. This article will review our present understanding of the adaptations in mineral metabolism that occur during pregnancy and lactation, and will focus on recent evidence that the breast itself plays a central role in regulating the adaptations during lactation.

Adapting to the transition between gestation and lactation: differences between rat, human and dairy cow

Adequate blood calcium concentrations are vital for the normal function of mammals. Mechanisms for maintaining normal blood calcium function adequately most of the time; however, occasionally they fail and calcium homeostasis is compromised. Milk fever or periparturient hypocalcemia in dairy cattle is a well-documented example of a breakdown in the mechanisms of calcium homeostasis. This disease occurs at the time of parturition and is unique to adult dairy animals. The disease results from the inability of animals to cope with the sudden demand for calcium in support of colostrum formation. Animals developing the disease become hypocalcemic and require intravenous calcium to survive. The precise metabolic disorder(s) responsible for the onset of milk fever is still being debated. This report will highlight some of the current concepts related to the causes and prevention of milk fever in dairy cattle, as well as contrasting differences in calcium demands that exist between dairy cattle, humans and rats at the onset of lactation.

Release of lead from bone in pregnancy and lactation

Concentrations and isotope ratios of lead in blood, urine, 24-h duplicate diets, and hand wipes were measured for 12 women from the second trimester of pregnancy until at least 8 months after delivery. Six bottle fed and six breast fed their infants. One bottle feeder fell pregnant for a second time, as did a breast feeder, and each was followed semicontinuously for totals of 44 and 54 months, respectively. Bone resorption rather than dietary absorption controls changes in blood lead, but in pregnancy the resorption of trabecular and cortical bone are decoupled. In early pregnancy, only trabecular bone (presumably of low lead content) is resorbed, causing blood leads to fall more than expected from hemodilution alone. In late pregnancy, the sites of resorption move to cortical bone of higher lead content and blood leads rise. In bottle feeders, the cortical bone contribution ceases immediately after delivery, but any tendency for blood leads to fall may be compensated by the effect of hemoconcentration produced by the postpartum loss of plasma volume. In lactation, the whole skeleton undergoes resorption and the blood leads of nursing mothers continue to rise, reaching a maximum 6-8 months after delivery. Blood leads fall from pregnancy to pregnancy, implying that the greatest risk of lead toxicity lies with first pregnancies.

Longitudinal changes in bone mineral density during normal pregnancy

Pregnancy is a common physiological event that could affect peak bone mass and the risk of developing osteoporosis later in life. There have been few longitudinal studies over a complete reproductive cycle of any size to show whether bone mineral density (BMD) changes. We have measured BMD by dual-energy X-ray absorptiometry in 46 normal women before conception and then again immediately after delivery and compared them with 30 control women who failed to conceive. Fifteen women were osteopenic in preconceptual BMD, but there was no difference between those who did or did not become pregnant. During pregnancy there was a small and statistically nonsignificant decline in BMD at all sites. The decrease at the trochanteric region was 4.2%, while losses at other sites were about 1%. The decline at the trochanter exceeded the least significant change between two measurements (5.04%) in 17 women (40.5%) with significant changes within individuals being much less common at the other measurement sites. The nonpregnant controls showed small increases in BMD of 0.3%-1.9% but no woman lost more than the least significant change. At the trochanter there was a significant difference (P = 0.013) between those who did and did not become pregnant. There was a good correlation between changes in BMD at all sites and no significant difference in the slope of these correlations between the pregnant and control groups. Correlations with lumbar spine were total hip, r = 0.46, P = 0.0001; femoral neck, r = 0.49, P = 0.0005; and trochanter, r = 0.66, P < 0.0001.

Calcium in pregnancy and lactation

Pregnancy and lactation are periods of high calcium requirement. This review highlights recent advances in our understanding of calcium and bone metabolism during human pregnancy and lactation and discusses the findings in relation to the calcium nutrition of the mother. The evidence indicates that pregnancy and lactation are characterized by physiological adaptive processes that are independent of maternal calcium intake and that provide the calcium necessary for fetal growth and breast-milk production without requiring an increase in maternal calcium intake. There are firm data that demonstrate that a low calcium intake during lactation does not lead to impaired lactational performance or to exaggerated bone loss. However, more research is required to define whether a low calcium intake prior to or during pregnancy can have deleterious effects on reproductive and lactational performance, and on the long-term health of the mother and child.

Effects of ovarian steroid hormones and thyroxine on calcitonin secretion in pregnant rats

In the present study, the roles of ovarian steroid hormones and thyroxine (T4) in regulating the secretion of calcitonin (CT) in pregnant rats were examined. The levels of plasma progesterone, pre- and post-CaCl2 plasma CT, and recovery time of plasma CT and calcium after calcium challenge were greatest in midterm pregnant rats. The levels of basal plasma progesterone, CT, calcium, and recovery time of plasma CT after calcium challenge were less in late pregnant rats, but basal plasma estradiol was highest in late pregnancy. The concentrations of plasma T4 were gradually decreased in rats during pregnancy. Regardless of the presence of estradiol, administration of progesterone in ovariectomized (Ovx) rats resulted in an increase of plasma T4 as well as the basal and calcium-induced secretion of CT. Administration of estradiol alone did not alter the CaCl2-induced levels but decreased the post-CaCl2 levels of plasma calcium in Ovx rats. The basal levels of plasma CT were decreased in Ovx rats treated with T4. These results suggest that the hypercalcitoninemia in midterm pregnant rats is due to an increased secretion of progesterone. Hypocalcitoninemia in late pregnant rats, however, is due in part to lower plasma calcium.