This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
Increased LDH in Acqueous Humor suggests a diagnosis of : 
Select and explain. 
A. Galactosemia, B. Retinoblastoma, C. Glaucoma, D. Gyrate atrophy
B: Retinoblastoma
Answer: B: Retinoblastoma 
Explanation: B i.e. Retinoblastoma Lactate Dehydrogenase Activity (LDH) is grossly increased in Retinoblastoma. LDH of aqueous humor is often used as a marker for RetinoblastomaQ Lactic Dehydrogenase (LDH) in Acqueous Humor -The enzyme Lactic Dehydrogenase (LDH) has been repoed to be present in small quantities in the normal aqueous humor where Isoenzymes 3, 4, and 5 predominate - The activity of Lactic dehydrogenase (LDH) in aqueous is measured as a ratio acqueous LDH / Plasma LDH. The LDH levels in aqueous is grossly increased in Retinoblastoma where the Aqueous/ Plasma ratio of LDH is usually greater than 1.5 (It is usually less than 0.60 in a variety of other conditions) The source of LDH in the aqueous of patients with Retinoblastoma is the release of cytosolic enzymes into the surrounding medium. Retinoblastoma is associated with a high degree of necrosis, which allows more free enzymes to reach the aqueous, and hence a high level of LDH is observed in patients with Retinoblastoma.