Hypercalcemia- Vitamin D Deficiency in Possible Hyperparathyroidism


Question

I have 66 year old lady with PHM Diabetes type II, obesity and hypertension. Referred by her GP with corrected Calcium mildly high at 2.68nmol/l (2.2-2.6), phosphate 1.07nmol/L , ALP normal PTH 6.2(1.1-6.9) as query hyperparathyroidism. Patient is completely asymptomatic and no weight loss.

No medication causing hypercalcemia. 24 hour urine for Cacium was non detectable 0.00 and Ca/Creatinine was 0.0. Vitamine D was defient at D2 <1.3 nmom/L D316.3 nmol/L.

U/S parathyroid showed thyroid nodule but no parathyroind nodule .

My question is is this primary hyperparathyroidims or secondary to vitamin D defiency ? how would i confirm this ? and would i have to treat with Vitamin D replacement despite teh hypercalcemia ?

Appreciate your help. Dr Yahya Mahgoub

Response

As the urinary calcium is very low, the diagnosis of FHH (Familial Hypocalciuric Hypercalcemic) should be considered. Conclusively diagnosed only by genetic testing, FHH may be diagnosed clinically if there is also a strong (autosomal dominant) family history of hypercalcemia. The vitamin D deficiency should be treated cautiously to avoid further increase in serum calcium. Primary hyperparathyroidism is still possible if the very low urinary calcium can not be confirmed; the absence of creatinine in the urine makes the test suspect. Secondary hyperparathyroidism is inconsistent with an elevated serum calcium, and there is no information regarding renal function. To be diagnostically useful, the serum phosphate must be done in the fasting state. Bone DXA would also be useful, and a 1, 25 dihydroxyvitamin D-mediated cause of hypercalcemia needs to be ruled out. Leonard J Deftos, MD