Bone mineral density and bone histomorphometric assessments of postpregnancy osteoporosis: a report of five patients

Pregnancy- and lactation-related osteoporosis: an important topic also for rheumatologists

<b>Objectives</b> <b>Material and methods</b> <b>Results</b> <b>Conclusions</b> <b></b> <b></b>

Pregnancy- and lactation-associated osteoporosis with vertebral fractures: a systematic review

BACKGROUND

To review, analyze and characterize the pregnancy and lactation-related osteoporosis (PLO) with vertebral fractures based on the extraction data in the previous studies.

METHODS

A comprehensive literature search of electronic databases including the PubMed, Embase and Web of Science was conducted from January 1st,1990 to December 1st, 2020. The enrolled data were pooled to analyze the baseline characteristics, clinical features, risk factors and treatment options.

RESULTS

A total of 65 articles with 338 cases were enrolled for data extraction. The enrolled cases aged from 19 to 47 years, with a mean value of 35.7 years old. The average body mass index (BMI) was 22.2 kg/m2 ranged from 16.0 to 39.0 kg/m2. Of the 173 cases, 149 cases with vertebral fractures occurred in the first pregnancy, 19 cases in the second pregnancy, four cases in the third pregnancy and one case in the fourth pregnancy. Up to 91.5% of the back pain occurred within the last 3 months of pregnancy and the first 3 months after delivery. The most involved vertebral levels were L2, L1 and T12 accounting for 32.6% of all the fractures. The average fracture numbers were 4.4 levels per patient. The lumbar Z-scores were mostly recorded with a mean value of - 3.2 ranged from - 7.8 to 0.

CONCLUSIONS

PLO with vertebral fractures is a rare clinical entity, which is more likely to occur in older and thinner pregnant women. Back pain is the clinical complaint and mostly occurs in the late pregnancy and early lactation periods. Most vertebral fractures appear in the first pregnancy but it can occur in any time of pregnancy. Thoracolumbar region is the mostly involved region. As compared with postmenopausal osteoporotic fractures, PLO usually has multiple levels fractures. Bisphosphonates are the most widely used treatment so far, however, many factors need to be taken into account to decide which drug to choose in PLO and further studies are necessary for clear recommendation in the future.

Women With Pregnancy and Lactation-Associated Osteoporosis (PLO) Have Low Bone Remodeling Rates at the Tissue Level

Pregnancy and lactation-associated osteoporosis (PLO) is a rare, severe, early form of osteoporosis in which young women present with fractures, usually multiple vertebral fractures, during late pregnancy or lactation. In studies of idiopathic osteoporosis (IOP) in premenopausal women, we enrolled 78 women with low-trauma fractures and 40 healthy controls, all with normal menses and no secondary cause of bone loss. In 15 of the affected women, the PLO subgroup, fractures had occurred during late pregnancy or lactation. We hypothesized that clinical, bone structural, and metabolic characteristics would differ between women with PLO and those with (non-PLO) IOP and controls. All were evaluated > 12 months postpartum, when structural and remodeling characteristics would be expected to reflect baseline premenopausal status rather than transient postpartum changes. As previously reported, affected subjects (PLO and IOP) had BMD and microarchitectural deficiencies compared to controls. Women with PLO did not differ from those with IOP in terms of age, BMI, body fat, menarcheal age, parity, or age at first pregnancy. However, women with PLO had a more severe clinical presentation than those with IOP: more fractures (5.5 ± 3.3 versus 2.6 ± 2.1; p = 0.005); more vertebral fractures (80% versus 17%; p < 0.001); and higher prevalence of multiple fractures. BMD deficits were more profound and cortical width tended to be lower in PLO. PLO subjects also had significantly lower tissue-level mineral apposition rate and bone formation rates (0.005 ± 0.005 versus 0.011 ± 0.010 mm² /mm/year; p = 0.006), as well as lower serum P1NP (33 ± 12 versus 44 ± 18 µg/L; p = 0.02) and CTX (257 ± 102 versus 355 ± 193 pg/mL; p = 0.01) than IOP. The finding that women with PLO have a low bone remodeling state assessed more than a year postpartum increases our understanding of the pathogenic mechanism of PLO. We conclude that women with PLO may have underlying osteoblast functional deficits which could affect their therapeutic response to osteoanabolic medications. © 2019 American Society for Bone and Mineral Research.

Pregnancy-related fractures: a retrospective study of a French cohort of 52 patients and review of the literature

A retrospective, multicentre study involving 52 patients was carried out to define the causes and characteristics of pregnancy-related osteoporosis. The mean number of vertebral fractures occurring during the last trimester of pregnancy or at the time of delivery was 3.8. This is often promoted by risk factors before or during pregnancy.

INTRODUCTION

In order to define the causes or predisposing factors of pregnancy-related osteoporosis and its clinical, radiological and bone density characteristics, laboratory findings, course and outcome, we carried out a retrospective multicentre study.

METHODS

The records of 52 women hospitalised over the last 10 years in the rheumatology departments of six French university hospitals and with a diagnosis of pregnancy-related osteoporosis were examined.

RESULTS

The patients' mean age at time of fracture was 32.1 years. In 10 patients, the fractures had occurred during the last trimester of pregnancy, and in 36 at the time of delivery or during the first 2 months post-partum. The mean number of vertebral fractures was 3.8 ± 2.0. Thirty three of the 52 patients had a risk factor of low bone mass before pregnancy. Twelve had disorders or treatments (heparin) that might promote osteoporosis during pregnancy, while 14 had no trigger factors before or during pregnancy. Overall, phosphate and calcium levels were normal, except for hyperphosphoraemia in lactating women (90%). On DXA scan, osteoporosis predominated in the trabecular bone (spinal T-score - 3.4, hip T-score - 2). Only 10 patients had a repeat fracture, and the increase in bone mineral density during follow-up was considerable, and improved by bisphosphonates (annual gain + 10% in the spine) or teriparatide (+ 15%).

CONCLUSIONS

Pregnancy-related osteoporosis gives rise to multiple vertebral fractures. It is often promoted by risk factors before or during pregnancy. Its mechanism is still unknown. Treatment with bisphosphonates or teriparatide appears to improve the recovery of bone mineral density.

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.

Pregnancy and Lactation-Associated Osteoporosis: Bone Histomorphometric Analysis and Response to Treatment with Zoledronic Acid

Pregnancy and lactation-associated osteoporosis (PAO) is a rare condition with little known pathophysiology. Most cases are diagnosed in the third trimester of pregnancy or in the first weeks postpartum, particularly in first pregnancies. Vertebral fractures are most commonly observed and characterised by prolonged severe pain, functional limitations and a loss of height. Measurements of bone mineral density and biochemical markers of bone remodelling are the clinical methods most commonly used for the management of these patients. However, a bone biopsy with histomorphometric analysis has been considered to be the gold-standard. Few studies have evaluated the histomorphometry in patients with this clinical condition and none of them performed the procedure at the beginning of the clinical assessment. In this study, we report a case of PAO in a 31-year-old postpartum patient who had undergone a twin pregnancy. We describe the clinical, laboratory tests and imaging features. Bone histomorphometry showed a high resorption rate and excellent evolution after 1 year of treatment with intravenous zoledronic acid. Our data suggest that osteoclastogenesis plays a central role in the pathophysiological processes of this disease.

Presentation and management of osteoporosis presenting in association with pregnancy or lactation

In this review, we summarize our current understanding of the pathophysiology of fragility fractures that occur for the first time during pregnancy and lactation, and provide guidance on appropriate investigations and treatment strategies. Most affected women will have had no prior bone density reading, and so the extent of bone loss that may have occurred during pregnancy or lactation is uncertain. During pregnancy, intestinal calcium absorption doubles in order to meet the fetal demand for calcium, but if maternal intake of calcium is insufficient to meet the combined needs of the mother and baby, the maternal skeleton will undergo resorption during the third trimester. During lactation, several hormonal changes, independent of maternal calcium intake, program a 5-10 % loss of trabecular mineral content in order to provide calcium to milk. After weaning the baby, the maternal skeleton is normally restored to its prior mineral content and strength. This physiological bone resorption during reproduction does not normally cause fractures; instead, women who do fracture are more likely to have additional secondary causes of bone loss and fragility. Transient osteoporosis of the hip may affect one or both femoral heads during pregnancy but it involves localized edema and not skeletal resorption. Case reports have described the use of calcitonin, bisphosphonates, strontium ranelate, teriparatide, vertebroplasty, and kyphoplasty to treat post-partum vertebral fractures. However, the need for such treatments is uncertain given that a progressive increase in bone mass subsequently occurs in most women who present with a fracture during pregnancy or lactation.

Osteoporosis presenting in pregnancy, puerperium, and lactation

PURPOSE OF REVIEW

To describe our current state of knowledge about the pathophysiology, incidence, and treatment of osteoporosis that presents during pregnancy, puerperium, and lactation.

RECENT FINDINGS

When vertebral fractures occur in pregnant or lactating women, it is usually unknown whether the skeleton was normal before pregnancy. Maternal adaptations increase bone resorption modestly during pregnancy but markedly during lactation. The net bone loss may occasionally precipitate fractures, especially in women who have underlying low bone mass or skeletal fragility prior to pregnancy. Bone mass and strength are normally restored postweaning. Transient osteoporosis of the hip is a sporadic disorder localized to one or both femoral heads; it is not due to generalized skeletal resorption. Anecdotal reports have used bisphosphonates, strontium ranelate, teriparatide, or vertebroplasty/kyphoplasty to treat postpartum vertebral fractures, but it is unclear whether these therapies had any added benefit over the spontaneous skeletal recovery that normally occurs after weaning.

SUMMARY

These relatively rare fragility fractures result from multifactorial causes, including skeletal disorders that precede pregnancy, and structural and metabolic stresses that can compromise skeletal strength during pregnancy and lactation. Further study is needed to determine when pharmacological or surgical therapy is warranted instead of conservative or expectant management.

Pregnancy-associated osteoporosis with a heterozygous deactivating LDL receptor-related protein 5 (LRP5) mutation and a homozygous methylenetetrahydrofolate reductase (MTHFR) polymorphism

Pregnancy-associated osteoporosis (PAO) is a rare, idiopathic disorder that usually presents with vertebral compression fractures (VCFs) within 6 months of a first pregnancy and delivery. Spontaneous improvement is typical. There is no known genetic basis for PAO. A 26-year-old primagravida with a neonatal history of unilateral blindness attributable to hyperplastic primary vitreous sustained postpartum VCFs consistent with PAO. Her low bone mineral density (BMD) seemed to respond to vitamin D and calcium therapy, with no fractures after her next successful pregnancy. Investigation of subsequent fetal losses revealed homozygosity for the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism associated both with fetal loss and with osteoporosis (OP). Because her neonatal unilateral blindness and OP were suggestive of loss-of-function mutation(s) in the gene that encodes LDL receptor-related protein 5 (LRP5), LRP5 exon and splice site sequencing was also performed. This revealed a unique heterozygous 12-bp deletion in exon 21 (c.4454_4465del, p.1485_1488del SSSS) in the patient, her mother and sons, but not her father or brother. Her mother had a normal BMD, no history of fractures, PAO, ophthalmopathy, or fetal loss. Her two sons had no ophthalmopathy and no skeletal issues. Her osteoporotic father (with a family history of blindness) and brother had low BMDs first documented at ages ∼40 and 32 years, respectively. Serum biochemical and bone turnover studies were unremarkable in all subjects. We postulate that our patient's heterozygous LRP5 mutation together with her homozygous MTHFR polymorphism likely predisposed her to low peak BMD. However, OP did not cosegregate in her family with the LRP5 mutation, the homozygous MTHFR polymorphism, or even the combination of the two, implicating additional genetic or nongenetic factors in her PAO. Nevertheless, exploration for potential genetic contributions to PAO may explain part of the pathogenesis of this enigmatic disorder and identify some at-risk women.

Effect of teriparatide on pregnancy and lactation-associated osteoporosis with multiple vertebral fractures

Pregnancy and lactation-associated osteoporosis (PLO) is very rare, but it can cause severe vertebral compression fractures with disabling back pain. PLO patients have commonly been treated with antiresorptive agents against high bone turnover. There are, however, some concerns regarding the use of bisphosphonates: (1) PLO occurs during the first pregnancy with a high possibility of recurrence during the second pregnancy, (2) long-term outcomes of bisphosphonates in PLO are lacking, and (3) there is a possibility of bisphosphonates accumulated in the bones crossing the placenta. Therefore, alternative therapies must be considered. We analyzed the effect of teriparatide (TPTD), the human recombinant parathyroid hormone (1-34), for 18 months in three women with PLO. Multiple vertebral fractures with severe back pain appeared within 6 months after their first childbirth. Two of them had a family history of osteoporosis. Lactation was discontinued immediately after diagnosis of PLO. Calcium carbonate, cholecalciferol, and TPTD were prescribed. The back pain immediately resolved. Bone mineral density (BMD) increased by 14.5-25.0% (mean 19.5%) at the lumbar spine and by 9.5-16.7% (mean 13.1%) at the femoral neck, after 18 months of treatment. The final Z scores in these PLO patients were nearly normalized. Two women had a second baby without any complication. BMD significantly improved after 18 months of treatment with TPTD without further fractures. In conclusion, TPTD should be considered to avoid long-term morbidity in young patients with PLO and is highly encouraged for use in PLO patients with multiple vertebral fractures.

Treatment with teriparatide in a patient with pregnancy-associated osteoporosis

INTRODUCTION

The decrease of BMD during a physiological pregnancy can in rare cases be intensified and lead to dramatic microarchitectural changes, which causes an increase incidence of fractures, preferably at the spine. This dramatic clinical picture is called pregnancy-associated osteoporosis.

CASE HISTORY

We present the case of a 40-year-old woman (gravida IV, para II) with acute back pain right after delivery due to four fractures of the spine. The diagnosis was confirmed by dual-energy X-ray absorptiometry measurement result (T-score -4.1 SD (0.598 g/cm(2)) at the lumbar spine (L1-L4), T-score -1.5 SD (0.759 g/cm(2)) at the total hip). Due to the severity of symptoms, a therapy with teriparatide (20 mg daily) was started for a period of 18 months.

RESULTS

After end of therapy, the T-score had significantly increased at the lumbar spine as well as at the hip (T-score of -2.1 (0.813 g/cm(2)) and -0.6 (0.864 g/cm(2)), respectively. The relative increase of BMD at the spine and total hip was 36% and 13.8%, respectively.

DISCUSSION

Our report demonstrates the successful use of teriparatide underlined by the increase of bone mineral density and the improvement of clinical symptoms in a case of severe pregnancy-associated osteoporosis for the first time.

The effect of pregnancy on pre-existing osteopenia: a case report

A 34-year-old Greek Cypriot lady (Mrs. AMC) P(2+0) booked at 10 weeks gestation with spontaneously conceived dizygotic twins. Her two previous uncomplicated pregnancies resulted in normal vaginal deliveries of male infants weighing 3.2 and 3.4 kg, respectively. Immediately following her second delivery, she underwent a manual removal of placenta (MRP) under general anaesthesia and sustained a fracture of the triquetral bone of her left wrist while being lifted off the operating table. Although she had complained of pain and restricted movement in her left hand after the MRP, the fracture remained undiagnosed for several weeks until an X-ray of her left wrist showed signs of delayed fracture healing of the triquetral bone. The pathological fracture was suggestive of osteoporosis during pregnancy but this was not investigated further at this stage. In 2004, she was referred to an orthopaedic surgeon with concern over a height loss of 3 cm in the preceding 6 months, as well as with generalised bony tenderness over her hips and lower back. Dual Energy X ray Absorptiometry (DEXA) to measure bone mineral density (BMD) revealed a T score of -1.6 SD (which is the WHO definition of osteopenia) in her right hip, which subsequently deteriorated to -1.8 SD (Table 1)

Bisphosphonates in pregnancy and lactation-associated osteoporosis

INTRODUCTION

Pregnancy and lactation-associated osteoporosis (PLO) is an uncommon condition characterized by the occurrence of fracture(s) during late pregnancy or the puerperium. The aetiology is uncertain, and its management and natural history poorly defined.

METHODS

We report a series of 11 women with PLO seen at our institution over the past 20 years, with follow-up ranging from 1 to 19 years.

RESULTS

Ten women presented with painful low-trauma vertebral fractures, at a median of 1 month postpartum. In nine cases the fractures were multiple (median: 3, range: 2-5). At least one recognised risk factor for osteoporosis (low body weight, smoking history, family history of osteoporosis/fracture, vitamin D insufficiency) was present in nine patients. Bone density was in the osteoporotic range at the spine (mean T score: -2.8), with less marked reduction at the proximal femur (mean T score: -1.9). Nine patients received bisphosphonate treatment, for a median duration of 24 months. In the five women who received a bisphosphonate within 1 year of presentation, spinal bone density increased by 23% over baseline values after 2 years of treatment (p=0.0014). Of the 5 women who had subsequent pregnancies, one, who had declined bisphosphonate therapy after the initial presentation, sustained a fracture in the postpartum period. Two patients (both of whom were followed for at least 10 years) sustained fractures outside of pregnancy.

CONCLUSIONS

PLO is therefore associated with significant morbidity, a high prevalence of recognized risk factors for osteoporosis and a risk of recurrence in subsequent pregnancies. Bisphosphonate therapy administered soon after presentation substantially increases spinal bone density in patients with PLO.

Effect of parity on bone mineral density in female rhesus macaques from Cayo Santiago

This cross-sectional study investigates the relationship between parity, bone mineral density, and spontaneous osteopenia/osteoporosis in a large skeletal population of female rhesus macaques (Macaca mulatta) from the free-ranging colony of Cayo Santiago, Puerto Rico. The sample consists of 119 mature female monkeys aged 4.0-22.2 years at time of death. The data consist of measurements of bone mineral content (BMC) and bone mineral density (BMD), obtained from dual-energy X-ray absorptiometry (DEXA) of the last lumbar vertebra. After controlling for age, there is a significant increase in BMD of the spine with increasing parity (P = 0.0006), up to a parity of 7 offspring. Thus, high parity initially has a positive effect on BMD in female rhesus monkeys, but this positive effect disappears with parities that are greater than 7 offspring. After controlling for parity, however, age has a negative (P = 0.015) effect on BMD, beginning several years after the attainment of peak BMD (age 9.5 years). Thus, it appears that parity initially mitigates the effects of aging, but the positive effect of parity on BMD is eventually overwhelmed by the aging process. Mean BMC and BMD values are higher in parous females compared to nulliparous females in the same age range. Similarly, females with low parity have significantly lower mean BMD values than do age-matched high-parity controls, and the frequency of osteopenia and osteoporosis is greater in low-parity females. Forty-three percent (43%) of the osteopenic/osteoporotic females in the sample are members of the low-parity group, even though it composes only 13% (16/119) of the entire sample. This study demonstrates that the free-ranging female rhesus monkeys from Cayo Santiago are a good nonhuman primate model for the study of bone mineral density, parity, osteopenia, and osteoporosis.

Pregnancy-associated osteoporosis with hypercalcaemia

Pregnancy-associated osteoporosis is an uncommon condition. It predominantly affects thinly built, primigravid, lactating women. These patients can sustain vertebral fractures with minimal or no trauma, resulting in significant morbidity. The association with hypercalcaemia is rare and typically occurs during the first few months postpartum, while lactating. This condition is, however, relatively benign and patients can expect to return to normal bone mineral density 6-12 months after breast-feeding has stopped.

Bone mineral density of alveolar bone in rats during pregnancy and lactation

BACKGROUND

The present study was designed to investigate the effect of pregnancy and lactation on the bone mineral density (BMD) of alveolar bone in rats fed diets containing different amounts of calcium (Ca). The effects of different levels of Ca intake by the mothers on the BMD of alveolar bone in their pups were also examined.

METHODS

Ten-week-old female Wistar rats were housed with male rats for breeding and were divided into 3 groups fed diets containing 0.9, 0.3, and 0.02% Ca, respectively. They were further divided into 2 groups according to pregnancy or non-pregnancy. Animals in the pregnant group were raised with their own pups for lactation. After the experiment, all animals were sacrificed, their mandibles were dissected, and soft x-ray microradiographs were taken to determine BMD in the interdental area with an image analyzer.

RESULTS

In both groups, BMD in alveolar bone decreased based on the amount of Ca in the diet, but the magnitude of this decrease was much greater in the pregnant group than in the non-pregnant group. There was no significant difference in BMD between 2 groups fed a 0.9% Ca diet. The BMD of alveolar bone in the pups also decreased depending on the amount of Ca in the diet.

CONCLUSIONS

The above results suggest that pregnancy and subsequent lactation could be risk factors for alveolar bone loss, especially under conditions of Ca insufficiency or deficiency and that Ca insufficiency or deficiency in the mother caused decreases in the BMD of alveolar bone in the pups.

A case of postpregnancy osteoporosis

A puerperant woman, who was previously healthy and had no disease known to affect bone metabolism, experienced lower back pain and lumbar vertebral fractures during lactation. Both bone formation markers and resorption markers were markedly elevated. Bone mineral density of the lumbar spine as measured by dual energy X-ray absorptiometry was extremely low. She stopped lactation through the use of bromocriptine because of the large volume of milk secretion. After treatment with calcitonin injections and the use of a corset, her back pain gradually disappeared. This case appears to be postpregnancy osteoporosis.

Changes in trabecular bone architecture in women during pregnancy

OBJECTIVE

To examine the effect of early and late pregnancy on the microarchitecture of maternal cancellous bone.

SAMPLE

Transilial bone biopsies were obtained from two groups of pregnant women one group (n = 15) in the first trimester and the other (n = 13) at term. Comparison was made with biopsy and autopsy samples from a group (n = 25) of normal premenopausal nonpregnant women.

METHODS

Undecalcified sections were analysed under a low power optical microscope using an automated trabecular analysis system which measures a comprehensive range of structural variables including the bone volume, trabecular number, width, separation and connectivity.

RESULTS

In early pregnancy the quantity of cancellous bone fell from a mean relative bone volume of 23.07% (SD 5.49) in nonpregnant controls to 16.72% (SD 3.91) (P < 0.001). This was primarily due to a decline in trabecular thickness from 122.9 microm (SD 10.5) to 97.2 microm (SD 21.8) (P < 0.01) and was accompanied by a loss of trabecular connectivity expressed as a reduction in the trabecular node: terminus ratio from 0.90 (SD 0.71) to 0.38 (SD 0.26) (P < 0.001). By late pregnancy the bone volume had been entirely restored to 23.41% (SD 9.76). This was primarily due to an increase in the number of trabeculae from 73.2 (SD 35.5)/field to 100.3 (SD 33.3) /field (P < 0.05)with an associated reduction in trabecular separation from 431 microm (SD 150) to 315.8 microm (SD 78.5) (P < 0.01).

CONCLUSIONS

Pregnancy affects the maternal skeleton by producing a fluctuation in the cancellous bone volume in which early temporary bone loss through trabecular thinning is restored in entirety through the addition of new trabeculae to produce a modestly more complex system of thinner more numerous bars by term.

Pregnancy-associated osteoporosis with elevated levels of circulating parathyroid hormone-related protein: a report of two cases

Two lactating women who had complained of back pain developed spontaneous vertebral fractures with low bone mineral density (BMD) several months postpartum. The back pain and biochemical abnormalities presented as hypercalcemia and elevated plasma levels of the parathyroid hormone-related protein (PTH-rP) that returned to normal indices with increasing BMD after weaning. The increased circulating PTH-rP might contribute to the pregnancy-associated osteoporosis in women who probably are already osteopenic.

Lumbar bone mineral density changes during pregnancy and lactation

OBJECTIVE

To elucidate the change of bone metabolism in the lumbar trabecular and its relationship with serum hormonal changes in pregnancy and lactation.

STUDY DESIGN

In a cross-sectional study, we measured the bone mineral density (BMD) of 2-4 lumbar vertebrae of 571 puerperae at days 3-5 postpartum and 341 healthy, non-pregnant women (control subjects) of approximately the same age by dual energy X-ray absorptiometry. In a longitudinal study, we also measured the BMD of 111 puerperae at 3 and 6 months after delivery.

RESULTS

The mean BMD at days 3-5 postpartum was significantly lower than that of the control (1.013+/-0.005 vs. 1.032+/-0.006 g/cm2, P = 0.019). The lactating group showed BMD decrement to 95.1+/-0.5% (n = 69) and 94.1+/-0.7% (n = 61) at 3 and 6 months postpartum, respectively, compared with days 3-5 postpartum, and the amenorrhea group showed the same tendency. The non-lactating group and resumption of menses group did not show a BMD decrement postpartum. In the lactating group, serum estradiol was significantly lower than in the non-lactating group at 3 months postpartum, serum prolactin and bone alkaline phosphatase levels were higher than in the non-lactating group at 3 and 6 months postpartum.

CONCLUSIONS

Pregnancy may cause a decrease of lumbar BMD, and the lactation and amenorrhea also cause a decrease of BMD. In addition to lactation status, the ovarian dysfunction is one of the factors in bone loss during lactation.

Bone structural and metabolic changes at the end of pregnancy and lactation in rats

OBJECTIVE

The objective of this study was to elucidate the net change of bone structure and metabolism in the lumbar trabecular bone of rats at the end of the pregnancy and lactation.

STUDY DESIGN

Female virgin Sprague-Dawley rats aged 200 days were mated, and bone mineral density by dual-energy x-ray absorptiometry, bone histomorphometry, and serum bone metabolic markers were measured at the end of pregnancy (day 22 of pregnancy), after delivery (day 5 post partum), and at the end of lactation (day 21 post partum).

RESULTS

At the end of pregnancy bone mineral density, bone volume, trabecular thickness, and serum calcium decreased; serum parathyroid hormone increased; and the histomorphometric parameters indicated that bone resorption were higher than those variables in nonpregnant rats, but bone formation was suppressed, as demonstrated by the low histomorphometric parameters and by the low serum alkaline phosphatase levels. After delivery the bone mineral density of nonlactating rats recovered rapidly, as in nonpregnant rats, but nonlactating rats showed more bone formation by histomorphometry than nonpregnant rats did. At the end of lactation, bone mineral density and serum calcium levels decreased considerably, and lactating rats showed substantial bone formation, bone resorption, and high serum alkaline phosphatase levels. The correlation between the number of pups (x) of the lactating and nonlactating groups and the bone mineral density (y, in grams per square centimeter) showed simple linear regression (y = -0.0067 . x +0.2517, r = 0.949, p < 0.0001).

CONCLUSIONS

These results indicate that significant decreases occur in the trabecular bone of rats at the end of pregnancy and lactation and that lactational intensity is related to bone mineral density.

Post-pregnancy osteoporosis (PPO)

Individuals with back pain during or immediately after pregnancy are suspect for postpregnancy osteoporosis (PPO). These patients are often diagnosed late if at all. This case report was selected to illustrate the presentation of such patients. Common criteria include back pain, spine fractures, occurrence in late pregnancy or within 3 mo postpartum, diagnosis made late, first pregnancy, height loss, lactation, mothers with osteoporosis, low bone density, some recovery of bone mass over years, and pre-existing osteopenia. Previous case reports and literature reviews show similar patient profiles.

Hazards of heparin: allergy, heparin-induced thrombocytopenia and osteoporosis

Heparin is the commonest mode of thromboprophylaxis used in pregnancy. It does not cross the placenta but has potential adverse effects on the mother, of which the most important is heparin-induced osteoporosis. The hazards of heparin, including bleeding, skin reactions, heparin-induced thrombocytopenia and osteoporosis are discussed and the relevant literature reviewed. Low-molecular-weight heparins have certain advantages over standard unfractionated heparins, especially in obstetrics. Their longer half-life and increased bioavailability enable once-daily injections, making them more convenient and acceptable. They are as effective as standard heparin but have a theoretically more favourable side-effect profile, providing less anticoagulant relative to antithrombotic activity. Current evidence suggests a lower incidence of heparin-induced thrombocytopenia. A reduced risk of osteoporosis is suggested but not yet proven. Although thrombo-embolism is currently the leading cause of maternal mortality in the UK, antenatal heparin prophylaxis is not given to all women with previous thrombo-embolism because of continued fears concerning heparin-induced osteoporosis. A protocol is presented with guidelines for different levels of obstetric prophylaxis depending on the perceived level of risk.

[Pathological phosphorus and calcium metabolism during pregnancy and breast feeding]

The occurrence of calcium and vitamin D deficiencies is enhanced during pregnancy and lactation. The presentation of parathyroid diseases is altered during gestation. A peculiar form of osteoporosis, pregnancy-associated osteoporosis, may be observed. Fetus and newborns suffer the consequences of all these disorders. The authors have reviewed the early detection and treatment of these diseases and emphasized their prevention.

[Osteoporosis in pregnancy: apropos of 2 cases]

Two women, 31 and 19 years old, developed acute back pain with non-traumatic vertebral fractures one month after delivery in one case, and during the 9th month of gestation in the second case. For the first patient, the evolution was favorable with an increase of bone mineral density (15.2% over fourteen months under calcium and vitamin D). Ten years later, the osteoporosis of the second patient worsened without any new pregnancy. Our observations suggest the possibility of different pathogenies in pregnancy-associated osteoporosis.

Bone quantity and quality in past populations

BACKGROUND

The study of osteoporosis in past populations offers valuable insight into the patterns and prevalence of the disease in both the past and in the present.

METHODS AND RESULTS

A review is made of different paleopathological studies better to understand bone loss in past populations and to examine the contribution such studies can make to our knowledge of osteoporosis in modern populations. The review includes studies of bone mass in past populations from different geographic regions. Nutritionally based hypotheses, traditionally used to explain bone loss in past populations, are reviewed and assessed against the current clinical and epidemiological findings. In general, the various studies have revealed different degrees of low bone mass in past populations; however, the pattern of bone loss and fragility seen in age-related and postmenopausal osteoporosis today is not evident in the past. Bone loss in earlier populations is often found in both sexes, whereas significant bone loss in females occurs often among the young-age categories. In addition, a prevalence of osteoporotic fracture is absent.

CONCLUSIONS

We suggest that, despite influences that may have reduced bone mass in past populations, a protection of bone quality may have occurred, reducing the likelihood of bone fragility and fracture typically seen in modern osteoporotics. It seems evident that, although reduced bone mass may be prevalent in past history, clinically recognized osteoporosis is not.

Osteomalacia and osteoporosis in a woman with ankylosing spondylitis

Three months postpartum, a 33-year-old woman with ankylosing spondylitis (AS) suffered multiple vertebral fractures. Bone mineral density was 61-67% of age-matched normal values at the lumbar spine and proximal femur, and an initial iliac crest bone biopsy revealed osteoporosis and osteomalacia. Secondary causes of bone disease were excluded, and the patient was treated with calcium, vitamin D, and nasal spray calcitonin (400 u/day). Over 4 years, she has shown partial recovery of bone mass and almost complete resolution of osteomalacia. Osteoporosis and fracture occur in patients with AS, yet this case represents a rare association between AS and both osteomalacia and postpregnancy spinal osteoporosis.

Osteoporosis in pregnancy

Osteoporosis has long been described in pregnant women who developed vertebral fractures in the last trimester or shortly after delivery without underlying disorders. However, this condition appears to be relatively rare and the clinical features, associated metabolic abnormalities and a pathological mechanism have not been fully established. This paper reviews available data on osteoporosis and pregnancy and briefly discusses the relationship between pregnancy and bone mass, calcium homeostasis, systemic skeletal hormones and local factors to help explain the pathophysiology of this unique disorder.

Transient osteoporosis of the hip in pregnancy: natural history of changes in bone mineral density

A 31-year-old white female developed severe bilateral hip pain during the third trimester of pregnancy that persisted after parturition. Laboratory abnormalities (elevated alkaline phosphatase and erythrocyte sedimentation rate) and radiographic changes (faint demineralization of the femur in the more symptomatic hip on plain films with evidence of bone marrow oedema and small joint effusions bilaterally on MRI) in the absence of other causes of focal osteoporosis were consistent with the diagnosis of transient osteoporosis of the hip in pregnancy. Although loss of bone mineral density (BMD) characterizes this syndrome, serial BMD measurements in symptomatic transient osteoporosis of the hip in pregnancy have not previously been reported. In the case reported here, serial bone density measurements were obtained over a 4-year period following the onset of symptoms. BMD in both femoral necks, which initially was approximately 20% lower than the average for age matched controls, increased markedly during the first year, plateaued during the following year, and then rapidly increased again following cessation of lactation. Unexpectedly, BMD in the lumbar spine, an asymptomatic site, was also markedly decreased at the time of presentation (31% lower than the mean of age-matched controls). Recovery of spinal density did not occur during the first year. However, spinal BMD did begin to increase during the second year and continued to rise after the cessation of lactation. In contrast to the marked reduction in bone density at these site of trabecular bone, cortical bone density in the forearm was normal. Possible aetiologies of pregnancy associated osteoporosis are discussed.