Hypoparathyroidism - Q-Notes for Adult Medicine

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The new england journal of medicine sions should follow to fully control symptoms and achieve safe and stable ionized calcium levels, usually above 1.0 mmol per liter. In the short term, the serum ionized calcium level should be measured frequently in order to monitor therapy (e.g., every 1 to 2 hours initially, while the infusion rate is being adjusted and until the patient’s condition has stabilized, and then every 4 to 6 hours). The recurrence of symptoms caused by hypocalcemia may indicate the need to increase the infusion rate and should be correlated with a simultaneous ionized calcium value to assess the progress of treatment. Oral calcium and vitamin D therapy should be initiated as soon as practical (Table 3). Intravenous infusions are generally tapered slowly (over a period of 24 to 48 hours or longer) while oral therapy is adjusted. Patients with low calcium levels (e.g., total calcium,
clinical practice ments maintained the serum calcium level within or slightly below the normal range (7.6 to 8.8 mg per deciliter [1.9 to 2.2 mmol per liter]), 4 but the use of PTH resulted in less urinary calcium excretion. Although PTH significantly increased biochemical markers of bone turnover (as compared with no significant change with calcitriol), there were no differences in bone mineral density between the groups. 4 Creatinine clearances did not differ significantly between the groups, and they were stable in both groups during the study. PTH (1–34) is not approved by the Food and Drug Administration for this indication. Limited data suggest that the quality of life may be compromised in patients with hypoparathyroidism despite treatment to optimize their biochemical values. In one study involving 25 women at a university center who were treated with vitamin D and calcium for postsurgical hypoparathyroidism, scores for somatization, depression, anxiety, and phobic anxiety were significantly higher than among age- and sexmatched controls with intact parathyroid function after thyroidectomy. 56 The effect of PTH replacement on quality-of-life measures is not known. Whereas most patients with mutations in the extracellular calcium-sensing receptor have mild hypocalcemia for which no treatment is required, 10,11 some have severe, symptomatic hypocalcemia necessitating therapy. Because treatment with calcium and vitamin D in these patients may exacerbate baseline hypercalciuria and result in nephrocalcinosis and renal insufficiency, PTH therapy may warrant particular consideration in these patients. Several patients have been treated successfully with PTH therapy, averting hypercalciuria and reduced renal function. 4 More data, however, are needed before its use can be recommended in practice. In the future, drugs that antagonize the extracellular calcium-sensing receptor (i.e., calcilytic agents), which are in development, might be used to stimulate endogenous PTH in such patients. Guidelines There are no formal guidelines for the management of hypoparathyroidism. Conclusions and Recommendations The initial evaluation of a patient with hypocalcemia should include a detailed family history (which may suggest a genetic cause) and relevant medical history (particularly regarding neck surgery and autoimmune disease). Laboratory testing should include measurements of serum total and ionized calcium, albumin, phosphorus, magnesium, and intact PTH levels. If the patient has severe symptoms, therapy with intravenous calcium should be initiated immediately, and the diagnosis pursued after the patient’s condition has been stabilized. In the patient described in the vignette, the hearing deficits and family history of renal disease suggest the diagnosis of the syndrome of hypoparathyroidism, deafness, and renal anomalies. The expectation is that the intact PTH level would be detectable but low. Given the absence of symptoms in this patient, outpatient treatment with calcium carbonate three times daily and calcitriol once or twice daily would be appropriate, with adjustment as needed to maintain a target level of albumin-corrected serum calcium at the lower end of the normal range (approximately 8.0 to 8.5 mg per deciliter [2.00 to 2.12 mmol per liter]), a 24-hour urinary calcium level well below 300 mg, and a calcium–phosphate product below 55. No potential conflict of interest relevant to this article was reported. An audio version of this article is available at www.nejm.org. References 1. Marx SJ. Hyperparathyroid and hypoparathyroid disorders. N Engl J Med 2000;343:1863-75. [Errata, N Engl J Med 2001;344:240, 696.] 2. Thakker RV. Genetics of endocrine and metabolic disorders: parathyroid. Rev Endocr Metab Disord 2004;5:37-51. 3. Goltzman D, Cole DEC. Hypoparathyroidism. In: Favus MJ, ed. Primer on the metabolic bone diseases and disorders of mineral metabolism. 6th ed. Washington, DC: American Society for Bone and Mineral Research, 2006:216-9. 4. Winer KK, Ko CW, Reynolds JC, et al. Long-term treatment of hypoparathyroidism: a randomized controlled study comparing parathyroid hormone (1-34) versus calcitriol and calcium. J Clin Endocrinol Metab 2003;88:4214-20. 5. Angelopoulos NG, Goula A, Rombopoulos G, et al. Hypoparathyroidism in n engl j med 359;4 www.nejm.org july 24, 2008 401 Downloaded from www.nejm.org at KAISER PERMANENTE on July 23, 2008 . Copyright © 2008 Massachusetts Medical Society. All rights reserved.
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