...For example, someone who, as a kid, suffered from Acute Glomerulonephritis, but has recovered and has had no complications ever since, what kind of effects, if any, would it have on the diver?
I would think someone, who as a kid suffered from Acute Glomerulonephritis and has fully recovered, would have no effects if he dives. Infection in the urinary tract does not predipose someone to a higher risk of diving illnesses, but if the disease is acute, and AT THAT PARTICULAR TIME this bloke chooses to dive, then the pain might be misconstrued to be DCS type of pain (abdominal pain..)
However, renal problems, for example renal failure can pose a serious problem in diving...Our kidneys act a filters, and when the kidneys are damaged by some systemic disease process, its ability to filter diminishes and products of metabolism such as creatinine and urea remains circulated in the bloodstream. When this happens, alteration in consciousness level and reduction in underwater skills occur, thus endangering the diver...
Hope that answers your question.