Diabetes insipidus is a condition in which there is a malfunction involving anti
ID: 3480683 • Letter: D
Question
Diabetes insipidus is a condition in which there is a malfunction involving antidiuretic hormone--ADC (also known as vasopressin) There are two forms of the disease. In central diabetes insipidus (CDI), the hypothalamus cannot secrete the hormone ADH, while in nephrogenic diabetes insipidus (NDI), the kidneys become insensitive to ADH. At left below are a list of symptoms. Drag each symptom to the appropriate box at right to indicate whether it would occur: (1) only in a patient with CDI, (2) only in a patient with NDI, (3) in patients with either condition, or (4) in neither type of patient. CDI patients only Both patient types Injecting ADH significantly increases urine osmolarity ADH levels below normal Large thirst and water intake ADH levels above normal Abnormally large urine volume Glucose in the urine NDI patients only Neither patient type Injecting ADH does not change urine osmolarity Abnormally high urine osmolarity ResetExplanation / Answer
CDI patients only
1. Injecting ADH will significantly increase urine osmolarity(as here deficiency of ADH is central)
2.ADH levels below normal(as ADH secretion from hypothalamus-posterior pituitary is low in central diab insipidus)
3. Large thirst and water intake
Nephrogenic diabetes insipidus
ADH levels above normal
Injecting ADH does not change urine osmolarity
Explanation: in nephrogenic DI
Issue is with renal receptors, ADH secretion is ok but it cant function properly due to receptor defect
ADH acts via V2 receptor present on the basolateral membrane of CD
V2 acts via cAMP and aquaporin channels
Water is reabsobed via aquaporin channels
Both patients type
Abnormally large urine volume
As ADH conserves water, urine volume becomes very high when ADH is less due to either central/renal reasons
Neither patients type
High glucose in urine
As it is diabetes insipidus and NOT diabetes mellitus
Pathophysiology of DI has nothing to do with glucose metabolism