Assessing Tubular Function in Kidneys

Questions and Answers

Patients are not allowed to drink after midnight.

7 am.

It refers to the amount of water given to the patient.

1200 ml. Signup and view all the answers

30 minutes. Signup and view all the answers

To avoid frequent urination during the night. Signup and view all the answers

To ensure a clean and empty bladder for the day. Signup and view all the answers

It helps ensure adequate hydration. Signup and view all the answers

The patient may need to rehydrate quickly. Signup and view all the answers

To restore and maintain appropriate hydration levels. Signup and view all the answers

Study Notes

Urine concentration test and urine dilution test are used to assess tubular function.
Specific proteinuria or tubular proteinuria, aminoaciduria, and phenosulfonphthalein test (PSP) are also used to evaluate tubular function.

Renal clearance tests depend on Glomerular Filtration Rate (GFR) and renal plasma flow.
GFR is normally 120 ml/minute and is calculated using the equation: C = (U x V) / P.
C represents clearance of the substance, U is the concentration of the substance in urine, P is the concentration of the substance in plasma, and V is the volume of urine passed per minute.

A normal GFR is 120 ml/minute.
A lower than normal GFR may indicate acute tubular necrosis, glomerulonephritis, shock, acute nephrotic syndrome, or surgery.
Approximately 40% of filtered urea is normally reabsorbed by the tubules.
The normal value of urea clearance is 75 ml/minute.

In cases of proteinuria, the specific gravity (S.G.) is elevated.
The earliest manifestation of renal disease may be difficulty in concentrating the urine.
A water load test can be used to assess the ability of the kidneys to concentrate urine. In this test, the bladder is emptied at 7 am, and then 1200 ml of water is given over the next 30 minutes.