Prevalence of vitamin A deficiency. Vitamin A deficiency (VAD) is a lack of vitamin A in humans. It is common in poorer countries but rarely seen in more developed countries. Nyctalopia (night blindness) is one of the first signs of VAD.revalence of vitamin A deficiency. Vitamin A deficiency (VAD) is a lack of vitamin A in humans. It is common in poorer countries but rarely seen in more developed countries. Nyctalopia (night blindness) is one of the first signs of VAD.
Both lithium and valproate have been reported to increase rat CSF GABA levels. Regarding valproate, animal studies reported that it enhances GABA levels, GABA synaptic release, GAD activity, neuronal GABA responsiveness, and inhibits GABA-T in several brain regions.
This is implicated with induction of suppressor T-cell activity specific for IgA. Agents that can cause IgA deficiency with such mechanisms include sulfasalazine, hydantoin, cyclosporine, gold, fenclofenac, sodium valproate, and captopril. Indeed, 20-40% of patients treated with phenytoin may develop IgA deficiency.