Aqueous humor lactic acid dehydrogenase in retinoblastoma

Thirty three patients underwent analysis for aqueous humor and serum lactic acid dehydrogenase (LDH) concentrations. By comparison of the ratios of aqueous humor LDH to serum LDH, the assayed patients fell into 3 catagories. There were 6 retinoblastomas for which ratios were calculated; all ratios in these cases were greater than 1.50. One case of active nematode endophthalmitis had a ratio of 1.03, presumably secondary to disruption of the blood vitreous barrier. The remainder of the cases (including other cases of nematode endophthalmitis, traumatic intravitreous and intraretinal hemorrhage, traumatic retinal detachment with rubeosis iridis, persistent hyperplastic primary vitreous, choroidal hemangioma, retrolental fibroplasia, pediatric cataracts, malignant melanomas, and senile cataracts) had ratios below 0.60. This separation of patients into retinoblastoma and nonretinoblastoma populations was done by a routine clinical laboratory assay.