Question

A 12 year old boy has a headache, malaise, and poor appetite. He complains of back pain. His mother notices that his face is puffy, especially around the eyes. She becomes alarmed when her son passes smoky-colored urine and immediately brings him in the clinic.

Patient’s history reveals that ten days ago, he had a bad sore throat, fever, and upper respiratory infection and missed several days of school. Physical examination reveals an inflamed pharynx, elevated blood pressure (145/100 mm Hg), abdominal distention, and swollen ankles. His height is 4 feet, 8 inches (1.42m) and his weight is 91 lb (41 kg). Blood urea nitrogen (BUN) concentration is 30 mg/dl (normal 7-18 mg/dl) and plasma creatinine concentration is 2.0 mg/dl (normal 0.8-1.3 mg/dl). A 24-hour urine sample was collected and had a volume of 900 ml and contained 1.30 g creatinine and 0.90 g protein. Microscopic examination of the urine sediment revealed odd-shaped red cells, red cell casts, and leukocytes.

A tentative diagnosis of post-streptococcal glomerulonephritis was made and was later supported by the finding of antibodies against streptococcal exotoxins in the patient’s serum. Certain strains of streptococci provoke an immunological response that damages the kidney’s glomeruli. Treatment with penicillin, diuretic drug, a reduced salt intake, and rest at home were prescribed.

The urine output increased immediately after treatment, and the puffiness in the face and hypertension promptly disappeared. The urine color became normal in a few days, but the urine tested positive for red cells and protein for several weeks. Laboratory values indicated normal renal function one year after this episode.

1. What is the patient’s 24 h urine volume? Is it normal?
2. Why is urinary protein excretion high?

Answer 1

The normal urine output should range around 1ml/kg/hr.Here the children weighs 41kg so in an hour the urine output should be 41ml .Therefore in a day it should be 984ml (41*24=984)

This suggests that the urine output is below the normal range .

The renal system plays a key role in the excretion of wastes. Due to the nephrons being affected in the glomerulonephritis, the protein excretion is altered resulting in increased excretion of this in the urine .Apart from this the condition like PGSN nephrotic syndrome results in proteinuria .In simple proteinuria is found in the acute phase of post streptococcal glomerulonephritis .