The test is for glucose, lipid panel and kidney. So I guess it's to get a more accurate cholesterol reading (It went up quite dramatically from normal levels to high levels after 3 months of low carb, but I was more pleased that the Trig/HDL ration was very low, which is apparently a good sign and the LDL value is just an estimate.)
The GP seemed a bit confused as to why it had gone up when I told her that I don't eat much food with saturated fats, and use low fat dairy and eat fish 3 or 4 times a week. There's the odd tablespoon of double cream (In meals for two) and not much cheese... (Not really a huge fan of cheese.) Fat is generally from nuts and olive oil. I eat eggs, but the body compensates for the cholesterol ingested by reducing its own production. (Unless you have a genetic condition, which I don't believe I have as I'd have been high before the low carb diet.)