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Thirst and passing too much water

Water Balance Problems - thirst and polyuria

As an endocrinologist and diabetologist I am well used to patients having problems with thirst and passing too much water. The most common reason to pass large volumes of water is diabetes mellitus.

Diabetes is derived from the term for siphon, to refer to the increased passing of water.

Diabetes mellitus refers to the sugar in the urine, mellitus means honey or sweet urine.

The other form of diabetes is diabetes insipisus; insipidus means 'bitter' urine.

One can infer what one likes about why someone would say one is bitter and one is sweet.

Diabetes insipidus is much much rarer than diabetes mellitus and the causes and treatment are completely different so it is important to distinguish the two.

Diabetes mellitus is usually easy to diagnose, there is glucose sugar in the water and the blood glucose is also elevated. There is a question to be answered of what type of diabetes mellitus is present, but that is bread and butter for a good diabetologist. There is quite a bit more than just saying whether the person has Type 1 or Type 2 diabetes.

Diabetes insipidus refers to a primary problem of the kidneys passing too much dilute urine because the kidneys fail to retain water correctly; consequently the patient drinks to replace the lost water.

A very similar clinical picture can also be due to over-drinking but the patient urinates to excrete the excess water that has been drunk - this is primary polydipsia. Primary because it is the starting problem. Poly - too much, dipsia - thirst

The two conditions are not a cleanly distinguished as it looks and this is difficult work for even the most experienced endocrinologist, sometimes requiring the patient to stay in hospital for a water deprivation test. Some people refer to primary polydipsia as dipsogenic diabetes. Dipso - thirst, genic - starting/ birth. That is diabetes born of thirst itself.

I attach a link here to a Fluid Balance Chart for patients to record their intake and output across the day if they have problems with thirst of polyuria and diabetes mellitus is excluded. Please reference the document if you use it and please do share the post and leave comments if you have any. If you like the post please do say so.

If you wish to consult someone about thirst and passing too much water it is usual to see your general practitioner first. They can often diagnose diabetes mellitus and refer on, and/or treat as necessary. If it is possible diabetes insipidus not only do you need to see an endocrinologist but someone trained to distinguish the different types of diabetes insipidus (starting from the brain or starting from the kidney) from primary polydipsia. That person should be trained to look for the causes, and some would often describe this as neuroendocrinology.

Dr Philip Kelly is an Endocrinologist, fully trained in neuroendocrinology and disorders of the pituitary and hypothalamus as well as diabetes insipidus of renal origin and diabetes mellitus. If you would like to see him please contact him via this page or visit the contact page at at LondonSwissMedical

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