Why am i drinking so much liquid?

for about 2 months i've been suffering with constant thirst and frequent urination. I wake up feeling hungover and every morning, severley dehydrated with a headache, i can't be dehydrated though as im drinking about 4-5 litres of water a day. I don't drink alcohol and im not diabetic [i got checked on monday] i'm going for a blood test on wed, but i just wondered if anyone has any theories as to what could be wrong?

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I agree with EricS wait for the result-it may be what he described(diabetes insipidus?)sorted with pituitary hormones.
Look it up-it's different to the other sort of diabetes.

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It could be a problem with your parathyroid glands. This would cause raised Calcium levels in your blood and your kidneys will do their best to get rid of it. If the next results don't show anything then ask about doing a 'bone screen'. This sounds weird but it seems to be the only blood test which checks Ca and some other things. If that comes back positive then you’ll need a parathyroid hormone test (more blood). The conditions for taking this are quite stringent and so the test is usually done in hospital.

If they find this then you can be treated, usually with an operation on your neck to remove the rogue gland (you have 4 so it isn't a problem). It isn't common and GPs often forget about the possibility so it is worth mentioning.

I’ve it and am waiting for the op - it took them 6 months to find it!!

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i saw a thing on tv about this girl with a problem like that because she was missing a hormone that regulates water level in the blood(her kidneys were in constant flush mode), wait for the blood test to come back, hers was just a matter of taking the hormone orally.

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i would have stated diabetes to begin with but if that's been checked,years ago i had a throat infection that i didn't know about,that left me thirsty and fatigued the whole time,doc said i was fatigued because my body was using energy to fight the infection,hope it goes well for you

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Well the only answer i could give would've been that you are diabetic. get checked out by your doc.

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the only answer that i can come up with is Type 1 diabeties. Are u sure cos they were my brothers symptons and he has now got diabeties