A 17-year-old boy is evaluated for abnormal urinalysis findings. He came to the clinic 2 weeks ago with low back pain, and a urinalysis at that time showed 2+ protein. He currently feels fine and has no urinary complaints. The patient has not exercised vigorously or taken any medications. He has no other medical problems and received all appropriate childhood vaccinations. He does not use tobacco or illicit drugs. The patient is not sexually active. His father had early coronary disease and a stroke. His blood pressure is 112/70 mm Hg and pulse is 77/min. BMI is 24 kg/m². Physical examination shows no abnormalities. Laboratory results from this visit are as follows: Urine sediment microscopy is unremarkable for casts. A 24-hour urine collection shows 600 mg of protein (normal <150 mg) .
Ultrasound of the kidneys shows no abnormalities. Split urine collection shows 40 mg of protein overnight (8 hours) and 500 mg of protein during the day (16 hours) . Which of the following is the best next step in management of this patient?

Question

A 17-year-old boy is evaluated for abnormal urinalysis findings. He came to the clinic 2 weeks ago with low back pain, and a urinalysis at that time showed 2+ protein. He currently feels fine and has no urinary complaints. The patient has not exercised vigorously or taken any medications. He has no other medical problems and received all appropriate childhood vaccinations. He does not use tobacco or illicit drugs. The patient is not sexually active. His father had early coronary disease and a stroke. His blood pressure is 112/70 mm Hg and pulse is 77/min. BMI is 24 kg/m². Physical examination shows no abnormalities. Laboratory results from this visit are as follows:

Urine sediment microscopy is unremarkable for casts. A 24-hour urine collection shows 600 mg of protein (normal <150 mg) .
Ultrasound of the kidneys shows no abnormalities. Split urine collection shows 40 mg of protein overnight (8 hours) and 500 mg of protein during the day (16 hours) . Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

Explanation: Long-term studies have shown that orthostatic proteinuria in adolescents is a benign condition that usually resolves spontaneously and does not have a significant effect on renal function. As a result, patients do not require further diagnostic workup or treatment (Choice D). Although very subtle glomerular abnormalities may be seen, orthostatic proteinuria has an excellent prognosis and does not predict development of significant glomerular pathology in the future. The patient should be reassured about the benign nature of orthostatic proteinuria and the tendency to resolve with age. He should be monitored periodically and have orthostatic proteinuria reconfirmed if he has persistent proteinuria. (Choice A) Angiotensin-converting enzyme inhibitors (or angiotensin II receptor blockers) are preferred for treating proteinuria due to glomerular damage (eg, diabetic nephropathy, glomerulonephritis, nephrotic syndrome). These medications reduce proteinuria and slow the progression of chronic kidney disease. However, orthostatic proteinuria has an excellent prognosis and does not require specific treatment. (Choice C) Oral prednisone is typically given empirically to children or adolescents with nephrotic syndrome due to minimal change disease. This patient's 24-hour protein <3-3.5 g makes this unlikely. (Choice E) First-degree relatives of children with nephrotic syndrome who do not respond to prednisone should undergo urine protein testing to diagnose rare genetic mutations that affect podocyte function. Educational objective: Orthostatic proteinuria is a benign finding and requires no invasive diagnostic workup (eg, kidney biopsy) or treatment (eg, angiotensin-converting enzyme inhibitors or oral steroids). References: Mechanisms of orthostatic proteinuria: lessons from a transplant donor. (http://www.ncbi.nlm.nih.gov/pubmed/8400067) Fixed and reproducible orthostatic proteinuria: results of a 20-year follow-up study. (http://www.ncbi.nlm.nih.gov/pubmed/7125410)

A 17-Year-Old Boy Is Evaluated for Abnormal Urinalysis Findings