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The Informed Parent

When An Abnormal Lab Test Is Not Really Abnormal

by Louis P. Theriot, M.D., F.A.A.P.
Published on Nov. 22, 2004

Ian was a five-year-old boy whom I had taken care of since he was born. My schedule indicated that he was coming in for his kindergarten physical. Glancing over his chart I was pleased to see that he had not been in the office since last year’s physical...obviously he had been quite healthy. It was a pleasure to do his exam because his growth, development and examination were textbook perfect. While talking to mom and filling out the physical form for school the nurse knocked on the door and handed me the results of his urinalysis that had been collected before. I was surprised to see that he had 2+ protein in his urine.

Jason was a 16-year-old high school sophomore who came in for his sports physical late one afternoon. He had on a sweatshirt, a pair of shorts, and running shoes, having just come from cross-country practice. “Thanks for doing my physical on such short notice,” he politely said. “We have our first meet next week. Coach said that if we didn’t have our physical forms completed by tomorrow we couldn’t run.” I got the history while mom was in the room. She indicated that everything was going quite well both academically and socially. Jason hadn’t been sick all year with the exception of some shin splints last March as a freshman. I had her step out of the room while I examined Jason, and then return afterwards. As I was filling out his physical form, I commented to mom how these athletes are in such great cardiovascular shape. Jason’s resting heart rate was 52 beats per minute, and the blood pressure was 110/70. The nurse handed me the results of his urinalysis and it showed that he had 2+ protein in the urine.

Myra was an 18-month-old baby who was brought to the office because of a high fever. “I felt she might be coming down with something at bedtime last night, but I didn’t think to take her temperature,” mom told me in a concerned voice. “Then, around 2 o-clock in the morning, I heard her moaning and she was just burning up. Her temperature was over 103 degrees!” By the time I saw Myra the temperature was down to 99.9 degrees. She was playful and not ill-appearing. She had an obvious right ear infection. But I told mom that I wanted to be sure she didn’t have a urinary tract infection too. Mom had mentioned that Myra’s urine had a strong odor to it. The results of the urine were somewhat surprising. While Myra did NOT have an infection, she had 2+ protein in her urine.

All three scenarios are very different, but they share the fact that each patient had 2+ protein in the urine. This can be the tip off of significant renal/kidney disease. However, as will be shown, the proteinuria (protein in the urine) in all three cases was completely benign and not a problem.

In Ian’s case there was little concern that he might have true kidney disease. He was growing so well, his blood pressure was normal and there was no family history of kidney pathology. Mom was told that I thought this might be a “postural condition” which is common, and of no consequence whatsoever. I instructed Ian to urinate right before going to bed, and told mom to discard this urine. Then mom was to collect his urine first thing in the morning before he even got out of bed. She was to label this specimen Night Urine. She was to collect Ian’s urine for the rest of the day until he went to bed. This would be labeled specimen Day Urine. The two separate specimens were then tested. The Day Urine measured 2+ protein, and Night Urine was completely negative for protein. This confirmed that Ian had Postural Proteinuria, also referred to as Orthostatic Proteinuria. Children with this condition excrete normal amounts of protein in the urine when in the lying down, or supine, position. In the upright position, the protein excretion may be increased ten-fold. In spite of this, children with Postural Proteinuria have normal kidney function and invariably have a completely normal work-up.

It was fairly certain that Jason did not have any kidney pathology for a number of reasons. His growth was normal, he was in great shape, and every urine that we had on record since he was two years old was normal. Mom was told that the proteinuria was probably due to Jason’s vigorous workout schedule in cross-country, but we needed to be sure that everything was, in fact, normal. I asked Jason to not run or work out on Friday, Saturday and Sunday. A first morning urine collection was needed on Monday. Jason brought it by the office on the way to school and nervously waited for the results. The urine specimen had not even a trace of protein in it. This confirmed that Jason had Exercise Proteinuria which is directly related to vigorous exercise. It is totally benign if it resolves after 48 hours of rest.

Myra did have an ear infection and was placed on antibiotics. Before she would start the antibiotics, I wanted to be sure she did not also have a urinary tract infection. Thus, we obtained a urinalysis and urine culture. It was felt that the 2+ protein in the urine was secondary to the high fever. Febrile proteinuria is not a rare finding in children with fevers over 101 degrees. It is a transient and benign condition. I had Myra come back for a follow-up in two days. The fever had resolved and she looked great. The urine culture was negative with no infection. I did a repeat urinalysis which was negative for protein. Myra’s mom was told that for completeness sake, I would check her urine for protein at her two-year well-check that was coming up in a month.

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