Hypercalcemia

Slight hypercalcemia is not associated with positive responses in the Comet Assay in male rat liver

Maintenance of physiological levels of intracellular and extracellular calcium is essential for life. Increased intracellular calcium levels are involved in cell death (apoptosis and necrosis) and are associated with positive responses in the Comet assay in vitro. In addition, high calcium and vitamin D intakes were reported to induce apoptosis in adipose tissue in obese mice and to increase DNA-migration in the Comet assay. To investigate increased serum concentration of calcium as a potential confounding factor in the regulatory Comet assay in vivo, we induced mild hypercalcemia in male Wistar rats by 3-day continuous intravenous infusion of calcium gluconate and performed the Comet assay in the liver in line with regulatory guidelines. The results of the study showed that mild increases in serum calcium concentration (up to 1.4 times above the concurrent control) and increased urinary calcium concentration (up to 27.8 times above the concurrent control) results in clinical signs like mild tremor, faster respiration rate and decreased activity in a few animals. However, under the conditions of the study, no increase in the %Tail DNA in the Comet assay and no indication of liver damage as determined by histopathological means were observed. Thus, mild increases in plasma calcium did not lead to positive results in a genotoxicity assessment by the Comet assay in the rat liver. This result is important as it confirms the reliability of this assay for regulatory evaluation of safety.

Vitamin D supplementation in older adults: searching for specific guidelines in nursing homes

BACKGROUND

The prevalence of vitamin D insufficiency is very high in the nursing home (NH) population. Paradoxically, vitamin D insufficiency is rarely treated despite of strong clinical evidence and recommendations for supplementation. This review aims at reporting the current knowledge of vitamin D supplementation in NH and proposing recommendations adapted to the specificities of this institutional setting.

DESIGN

Current literature on vitamin D supplementation for NH residents was narratively presented and discussed by the French Group of Geriatrics and Nutrition.

RESULT

Vitamin D supplementation is a safe and well-tolerated treatment. Most residents in NH have vitamin D insufficiency, and would benefit from vitamin D supplement. However, only few residents are actually treated. Current specific and personalized protocols for vitamin D supplementation may not be practical for use in NH settings (e.g., assessment of serum vitamin D concentrations before and after supplementation). Therefore, our group proposes a model of intervention based on the systematic supplementation of vitamin D (1,000 IU/day) since the patient's admission to the NH and throughout his/her stay without the need of a preliminary evaluation of the baseline levels. Calcium should be prescribed only in case of poor dietary calcium intake.

CONCLUSION

A population-based rather than individual-based approach may probably improve the management of vitamin D insufficiency in the older population living in NH, without increasing the risks of adverse health problems. The clinical relevance and cost effectiveness of this proposal should be assessed under NH real-world conditions to establish its feasibility.

Vitamin D hormone: a multitude of actions potentially influencing the physical function decline in older persons

Vitamin D, a secosteroid (pro)-hormone, has been traditionally considered as a key regulator of bone metabolism, and calcium and phosphorous homeostasis through a negative feedback with the parathyroid hormone. However, during the last 20 years, the role played by vitamin D has been largely revised by recognizing its pleiotropic action on a wide spectrum of systems, apparatuses and tissues. Thus, vitamin D has growingly been involved as a primary determinant of biological modifications and specific clinical conditions. The effect of vitamin D on skeletal muscle and related outcomes (including physical function decline and disability) is surely one of the most relevant to study in the context of global aging. In the present review, the subclinical and clinical consequences of vitamin D deficiency/insufficiency, extremely frequent conditions in older age, are described. Special focus is given to skeletal muscle and physical function. Limitations of available scientific evidence on the topic are also discussed.

Differential RNA expression profile by cDNA microarray in sporadic primary hyperparathyroidism (pHPT): primary parathyroid hyperplasia versus adenoma

BACKGROUND

Differential diagnosis between adenoma and hyperplasia in primary hyperparathyroidism (pHPT) remains a dilemma. The aim of this study was to assess differences in transcriptional genomic expression profiles between sporadic (nonfamilial) parathyroid hyperplasia (SPH), adenoma, and normal tissue.

METHODS

Parathyroid tissue from 12 patients with parathyroid adenoma, 3 with SPH, and 2 with normal glands was selected for analysis. Histopathology was reviewed in all cases, and all patients with adenomas presented normocalcemia for a minimum of 6 months after one gland resection. Hybridizations were performed in a microarray containing 19,968 human cDNA clones including contiguous replicates. Direct comparisons were performed with reverse labeling for every different pooled sample entity. Expression levels were analyzed using the SAM, SMA, LIMMA, Cluster, and PAM packages in the R environment for statistical computing.

RESULTS

There were significant statistical differences between SPH and adenomas. In the direct comparison, a total of 200 genes showed differential expression (P < 0.03): 61 genes were upregulated (> 1.65-fold increase) and 139 were downregulated (> 1.58-fold decrease) with a B value > 4.68 (99.08% probability of real differential expression). When SPH was compared to normal parathyroid tissue, 50 genes were differentially expressed: 42 were upregulated (> 1.89) and 8 were downregulated (> 1.7) with a B > 4.26 (98.6% probability of real differential expression). At least 17 genes were differentially expressed and able to discriminate SPH from adenoma or normal tissue. Upregulated genes were related to apoptosis inhibition, cell proliferation, transcriptional activity and cell adhesion, among other activities. Downregulated genes were mainly related to ion channel activity, lipopolysaccharides, prostaglandin-d synthase, and integral membrane proteins.

CONCLUSIONS

Our data suggest that SPH and adenoma have a singular molecular signature that, theoretically, could be used for the differential diagnosis of these entities and normal parathyroid tissue.

Laboratory screening for hyperparathyroidism

INTRODUCTION

The clinical syndrome produced by excess parathyroid hormone (PTH) is referred to as hyperparathyroidism (HPT). Autonomous growth of PTH producing cells is defined as primary hyperparathyroidism (pHPT). In its classic form pHPT is characterized by painful bones, kidney stones, abdominal groans, psychic moans, fatigue overtones and hypercalcemia. Chronic stimulation of the parathyroid glands secondary to low circulating calcium level results in secondary hyperparathyroidism (sHPT). Tertiary hyperparathyroidism (tHPT) results from prolonged secondary hyperparathyroidism when the glands take on an autonomous function manifested by hypercalcemia and high PTH levels despite resolution of the original stimulus.

REVIEW

The paper reviews the physiologic regulation of PTH secretion and types and forms of HPT. Calcium homeostasis is discussed, emphasizing interactions of PTH, PO4 and vitamin D that can lead to HPT. In addition, the paper reviews the contribution of serum calcium, chloride, phosphorus and PTH levels to the diagnosis of HPT, the role of urinary calcium in the diagnosis of familial benign hypocalciuric hypercalcemia (FBHH), and the role of alkaline phosphatase and bone mass measurements as markers of severity of hyperparathyroid bone disease.

CONCLUSIONS

It is concluded that the diagnosis of hyperparathyroidism can be made with a very high confidence rate by documenting an increased serum PTH level with an increased ionized or total calcium level in pHPT, increased serum PTH level with low or normal calcium level and an underlying renal failure or vitamin D deficiency in sHPT. Early management of HPT is important because many of the nonspecific complains, or classic symptoms, or metabolic conditions often improve after proper control of hyperparathyroidism.

Primary hyperparathyroidism: a case study

Primary hyperparathyroidism is a hypercalcemic condition generated as a result of overproduction of parathyroid hormone (PTH) by one or more of the parathyroid glands. The cause is usually an abnormal group of cells forming a benign adenoma and rarely carcinoma. The condition is usually discovered by routine serum chemistry analysis showing hypercalcemia, hypophosphatemia, and elevated PTH levels. Elevated 24-hour urine calcium provides further confirmation. During the last decade, three procedures have been developed to help diagnose the affected parathyroid gland(s) in preparation for surgical intervention: computerized nuclear scanning with technetium-99-m sestamibi performed preoperatively; radio-guided probes; and rapid PTH assay (RPHA), both used intraoperatively. These three techniques have been reported to reduce the need for immediate frozen section diagnosis; shorten the length of the incision, surgical time, and length of hospital stay; produce less pain and discomfort; reduce surgical cost; and produce a quicker return to normal life. This article follows the surgical experience of a patient with a diagnosis of hyperparathyroidism and a history of postoperative nausea and vomiting who was scheduled as 23-hour stay.