A man has a urine output of 6 to 8 L/day. He presents with hypernatremia, dehydration, and his antidiuretic hormone (ADH) level is very low. Although he has had no intake for 4 hours, there is no change in his polyuria. These are indications of:

Diabetes Insipidus

Explanation:

Diabetes Insipidus is a rare condition that affects the kidneys ability to prevent excretion of water hence a lot of urine is produced.

This condition is caused by a damage in the pituitary gland or hypothalamus  hence affecting the usual production of ADH which is responsible of controlling the amount of water in the urine.

Therefore, a patient who presents polyuria, hypernatremia , dehydration and low levels of ADH is an indication of Diabetes insipidus.

Answer

It is an indication of Diabetes Insipidus. However because his ADH levels is very low, then it is Central Diabetes Insipidus(CDI) or Neurologic Insipidus.

Generally diabetes insidpidus is a clinical disorder due to disruption  of the body electrolyte fluid balance,leading to  increase in solute potential of the blood,   polyuria and polydipsia. it is caused by infections, tumors, trauma, autoimmune diseases to the  pituitary gland .

Specifically Central Diabetes Insipidus (CDI) is due to lack  of ADH  production in the hypothalamus. Since ADH  promotes  water re-absorption at the kidneys  to increase blood  volume,when solute potential of the blood increases during Hypernatremia, lack of ADH leads to increase in blood solute potential, from  production of  larger quantity of  diluted urine -polyuria, and therefore polydipsia(great thirst), which depletes the blood of fluids and therefore rise in solute potential.

The fact that the polyuria remains the same despite no intake for 4hrs,is due to  lack of   ADH  and therefore failure  to stimulate  re-absorption of water at the collecting duct, thus as the kidney produces urine, this is coming out with no re-absorption of water back to the blood,Therefore large diluted urine will continuously be produced.

Note - the condition is related to diabetes  mellitus  because of  the polyuria, symptoms, it has no other correlation with diabetes mellitus outside this.

Explanation:

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