The patient is an 18 year old male who noted the onset of severe headache and markedly increased urination about 4 years prior to admission. He stated that the onset of the increased urination had been dramatic and abrupt and he could recall the exact day it had begun. He said that he would urinate 10-12 times during the waking hours and would have to get up 5-6 times per night for further urination. He said he had an intense thirst with the craving for ice cold beverages and consequently during the last few months had been consuming vast quantities of water, but he seemed quite sure that the increase in urinary frequency preceded the increase in drinking. As an outpatient he, on the advice of his doctor, made a 24-hour urine collection and the volume of that collection was 5 liters.

He further stated that he never developed body or facial hair and had never shaved. He felt embarrassed that while the voices of many of his friends were deepening, he was still a soprano. Although he tried to involve himself in vigorous body building activity, he felt that his muscular development was lacking. He also lacked libido and had been unable to have an erection for about one year.

He said that he had been growing until the age of 14 years when his growth simply ceased. Over the time course of all these symptoms, he felt generally tired and depressed.

Although the patient has been generally healthy prior to the onset of the current symptoms, it is notable that 6 months ago he was involved in an automobile accident. His car was hit in the rear when he was switching from the center to the left lane and did not see the care coming up beside him.

The patient was alert and oriented to person, time and place. Pulse - 56/min; blood pressure - 110/70 mmHg; respiratory rate 16/min; temperature - 96 F; height - 65 inches; weight - 135 pounds.

Neck Thyroid not palpable.

Chest Bilateral white liquid was expressed with forcible squeezing from his nipples.

Lungs Clear

Heart S1 and S2 were normal. There was no S3, S4 or murmurs.

Abdomen Unremarkable

Extremities Within normal limits

Skin Cool, dry, pale.

Hair Very little hair was found on the face or in the axillary or pubic areas.

Glucose = 100 mg% (nl 70-110); sodium = 145 mEg/L (nl 135-145); potassium = 4 mEg/L (nl 3.5-4.5); chloride = 100 mEg/L (nl 98-108); CO2 = 24 mEg/L (nl 20-32); calcium = 9.4 gm% (nl 8.9-10.3); BUN = 30 mg/dl (nl 7-22); creatinine = 0.9 mg/dl (nl 0.7-1.5). Urinalysis was negative with a s.g. of 1.001

Time Weight B.P. Pulse Urine Osm. Plasma Osm. Urine

(hrs) (lbs) (mmHg) (bts/min) (mOsm/Kg) (mOsm/Kg) Output

0 135 110/80 58 75 305 300

1 135 110/80 58 75 350

2 134 110/80 54 70 350

3 133 108/70 54 78 310 300

4(5 U AVP) 133 108/70 54 200 100

5 133 110/80 54 400 50

6 133 110/80 54 800 280 50

Serum AVP unmeasurable just before exogenous AVP was given.

MRI scan - large mass with supra sella extension.

Questions

1. What is the cause of this patient’s polyuria?