The influence of coenzyme Q(10) on total serum calcium concentration in two patients with Kearns-Sayre Syndrome and hypoparathyroidism

Two patients with Kearns-Sayre Syndrome and hypoparathyroidism were treated with alfacalcidol (1a-OH D-3) and total serum calcium concentration remained within normal range for a long period. After two months of combined therapy with Coenzyme Q(10) (CoQ(10)), hypercalcemia was noticed and as a result, 1a-OHD3 was gradually discontinued. Normal total serum calcium concentration was obtained with CoQ(10) monotherapy while the replacement of CoQ(10) with placebo led to hypocalcemia. The mechanism of action of CoQ(10) is difficult to explain. Since the parathormone level remained unchanged during CoQ(10) or placebo therapy, we speculate that the capacity of producing an active form of vitamin D in mitochondria of proximal tubules was restored by CoQ(10) therapy.