Hypocalcaemia in HIV infection and AIDS

Objectives. To study the prevalence and possible mechanisms of hypocalcaemi a in HIV infection and AIDS. Subjects. 828 patients with HIV infection or AIDS and 549 controls. Interventions. Measurements of total serum calcium and albumin levels. Para meters of calcium homeostatsis were determined in a subgroup of 21 hypocalc aemic AIDS patients. Results. Mean serum calcium was 2.34 +/- 0.13 mmol L-1 in the HIV group vs. 2.46 +/- 0.10 mmol L-1 in controls (P < 0.0001). After adjusting for serum albumin, hypocalcaemia was present in 6.5% of the HIV group vs. 1.1% of co ntrols. Mean serum calcium was declining according to CDC groups, and diffe red significantly from controls in each group. Regression coefficients of c acium vs. albumin were 0.147 amongst HIV-infected patients and 0.106 for co ntrols. In the subgroup of hypocalcaemic patients with AIDS, 10/21 had vita min D deficiency six of these with low ionized calcium levels. Low serum PT H was found in 2/21 patients, Magnesium deficiency in 1/21. Of the remainin g eight patients, only one had secondary hyperparathyroidism, while the oth er seven lacked an adequate PTH response, despite low ionized calcium level s in four subjects. Conclusions. Mean serum calcium concentrations were lower through all CDC s tages, irrespective of albumin, resulting in a higher prevalence of hypocal caemia in HIV-positive patients compared with controls. In a considerable n umber, this seems to be caused by vitamin D deficiency and potentially a la ck of adequate PTH secretion, but further studies are needed to confirm thi s.