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PRIMARY HYPERPARATHYROIDISM WITH INTERMITTENT HYPERCALCAEMIA: SERIAL OBSERVATIONS AND SIMPLE DIAGNOSIS BY MEANS OF AN ORAL CALCIUM TOLERANCE TEST
Author(s) -
BROADUS A. E.,
HORST R. L.,
LITTLEDIKE E. T.,
MAHAFFEY J. E.,
RASMUSSEN H.
Publication year - 1980
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1980.tb02704.x
Subject(s) - hypercalcaemia , medicine , endocrinology , primary hyperparathyroidism , calcium , hypercalciuria , hyperparathyroidism , basal (medicine) , metabolic disorder , diabetes mellitus
Ten patients with subtle primary hyperparathyroidism and intermittent hypercalcaemia were followed serially for periods of 2–18 months (mean 10 months). Fasting serum calcium was elevated (< 10·6 mg/dl) in only 20% of determinations and fluctuated widely (9·1–11·2 mg/dl), yet the patients displayed a continuous, rather than episodic, basic disease process as defined by increases in nephrogenous cyclic AMP and serum iPTH. Identical findings were noted in short‐term (2–3 successive days) studies in twelve patients. In response to a 1000 mg oral calcium tolerance test, twelve patients with primary hyperparathyroidism and intermittent hypercalcaemia (basal serum calcium 10·2 ± 0·2 mg/dl, mean ± SD) displayed: (1) hyperabsorption of calcium (mean calciuric response twice normal); (2) induced‐hypercalcaemia (mean serum calcium 11·4 mg/dl, with a mean increase of 1·2 mg/dl versus 0·2 mg/dl in normal subjects); and (3) abnormal parathyroid suppressibility (nephrogenous cyclic AMP 2·66 ± 0·57 nmol/100 ml GF versus 0·95 ± 0·40 nmol/100 ml GF in normal subjects, mean ± SD). The patients demonstrated striking hypercalciuria (452 ± 123 mg/24 h) on a 1000 mg metabolic calcium diet. Serum levels of 1,25(OH) 2 D 3 , measured in ten patients, were markedly elevated at 90 ± 20 pg/ml (mean ± SD), and there was a strong positive correlation between the values for 1,25(OH) 2 D 3 and the calciuric response to the calcium tolerance test (r=0·75, P <0·001). These results (1) indicate that the calcium tolerance test is a simple and reliable technique for diagnosis of patients with primary hyperparathyroidism and intermittent hypercalcaemia, and (2) emphasize the important pathophysiologic features of this subtle clinical variant of primary hyperparathyroidism.