The nurses admiting a school-age child in acute renal failure o reduced glomerular filtration rate. Which urine test is the most useful clinical indication of glomerular filtration rate?

Creatinine is a waste product generated by muscle metabolism and excreted by the kidneys. It is commonly used as a marker of renal function because it is filtered by the glomeruli and almost entirely excreted in the urine. When there is a reduction in GFR, as in acute renal failure, creatinine levels in the blood tend to rise. Elevated serum creatinine levels are indicative of impaired kidney function and a decreased GFR.

The other options are not direct indicators of GFR:

A. Protein level: While proteinuria (elevated protein levels in urine) can be a sign of kidney dysfunction, it is not a direct measurement of GFR. Proteinuria can occur for various reasons, including glomerular damage, but it doesn't provide a precise assessment of GFR.

C. Osmolality: Urine osmolality reflects the concentration of solutes in urine but is not a direct measure of GFR. It can provide information about the concentrating ability of the kidneys, but it doesn't assess the overall filtration rate.

D. pH: Urine pH is a measure of the acidity or alkalinity of urine and is not a direct indicator of GFR. It can be influenced by factors such as diet and renal tubular function but does not directly measure the filtration rate of the glomeruli.

The presence of leukocytes, nitrates, and blood in the urine, along with a urinary pH of 6.5, is suggestive of a urinary tract infection (UTI). Additionally, symptoms such as frequent urination, pain or discomfort during urination, or other urinary symptoms may also be present in UTIs.

The other options (A, B, and D) are less likely based on the provided information:

A. Nephrotic syndrome typically presents with significant proteinuria and edema but may not show the specific findings seen in a UTI urinalysis.

B. Acute glomerulonephritis may have different urinalysis findings, including hematuria and proteinuria, but the presence of nitrates and leukocytes in the urine is not a typical feature.

D. Diabetes mellitus Type 1 may have glucose in the urine, but the presence of nitrates, leukocytes, and blood in the urine is more indicative of a UTI than diabetes.