evidence in this differentiation, although the usefulness of this test has been disputed (Milne, 1951 ; Dent, 1953 MacGregor and Whitehead, 1954).Of great interest, however, is the finding in our case of normal or high levels of calcium excretion in the urine.Reviews of published cases of idiopathic hypoparathyroidism (Lachmann, 1941; Steinberg and Waldron, 1952) are reticent on the matter of urinary calcium content.The records of most cases contain bare statements that the Sulkowitch test was either " negative " or "faintly positive "-findings which, according to Albright and Reifenstein (1948), indicate blood calcium levels of "below 7.5 mg. per 100 ml."They further admit, however, that certain individuals apparently have a low renal threshold for calcium excretion, and mention, without further details, three patients with hypopara- thyroidism who excreted large amounts of calcium in the urine at low levels of serum calcium.It would appear preferable, where possible, in further studies of cases of hypoparathyroidism to substitute for the Sulkowitch test the more precise assay of daily calcium excretion.It does not seem to us adequate to regulate the calciferol dosage by the Sulkowitch test without periodic checks upon the serum calcium level.In our own case the absence of other urinary abnormality, together with the increase in urinary calcium excretion parallel with elevation of the serum calcium, suggests an abnormality of renal threshold for calcium, an "idiopathic hypercalciuria."There is no evidence of osteoporosis, and the radiological abnormalities typical of hypoparathyroidism suggest that the hypercalciuria is no more than an incidental unassociated abnormality. SummaryA case of idiopathic hypoparathyroidism presenting with epilepsy is described.Restoration of normal serum levels of calcium and phosphate was achieved with calciferol in high dosage.The unusual finding of a high normal daily calcium excretion in the urine before treatment is discussed.Our thanks are due to Mr. W. M. Nichols for
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Owen et al. (1959) studied this question.