Question

Endocrine Case Histories - Case 25

A 28-year-old male complained of abrupt polydipsia and polyuria. Blood and urine analyses provided the following results:

Fasting blood glucose	93 mg/dL
Serum sodium	145 mEq/L
Serum potassium	2.8 mEq/L
Urine specific gravity	<1.005
Urine osmolality	<200 mOsm/L
Urine volume	15 L/day
Urine glucose	0

Water deprivation and hypertonic saline infusion do not cause a significant reduction in the polyuria and concentration of urine. Complete water-deprivation results in the following:

Urine specific gravity	1.009
Urine osmolality	225 mOsm/L

However, there is a significant concentration of the urine and a decrease in urinary output following administration of ADH.

1. Define polydipsia and polyuria.

2. Why did the water deprivation and hypertonic saline infusion not result in a concentrated urine?

3. Describe the location of the disorder in this individual.

4. A nasal spray containing a synthetic substance was self-administered to treat this condition. What type of compound was present in the nasal spray?

5. Discuss the hypothalamic-pituitary-target organ pathway for this individual and indicate the normal and pathophysiological conditions involved.

Answer 1

1.
Polyuria : production of abnormal big volumes of dilute urine.
Polydipsia : abnormal thirst is a symptom of disease or psychological disturbance

2.
Water deprivation & hypertonic saline infusion does not result in a concentrated urine beacuse kidneys are unable to respond due to prolonged intake of large volumes of water.

3.
Diabetes Insipidus results from a deficiency of vasopressin due to a hypothalamic-pituitary disorder or from resistance of the kidneys to vasopressin. polydipsia and Polyuria develop

4.
Desmopressin or Lypressin is the compound present in the nasal spray