Some diagnostic tests are less accurate when performed in pediatric patients with impaired kidney function, according to research published April 14 in the Journal of Applied Laboratory Medicine. These findings show that health care providers should assess patient kidney function when interpreting clinical test results for certain conditions to ensure that patients receive the correct diagnoses and treatments.

Because the kidneys filter some biomarkers, it is suspected that impaired kidney function could lead to decreased accuracy of diagnostic tests that measure biomarkers. In this study, scientists led by Lars Mørkrid, MD, PhD, of Oslo University Hospital, Norway, have found that impaired kidney function impacts tests for creatine deficiency syndromes, acute kidney failure, and ovarian cancer.

To determine this, the researchers measured the blood and urine levels of three biomarkers—guanidinoacetate (GAA), neutrophil gelatinase-associated lipocalin (NGAL), and human epididymis protein 4 (HE4)—in 96 children with chronic kidney disease, and evaluated participant kidney function using measured glomerular filtration rate (mGFR).

When mGFR the researchers observed significant drops in serum GAA and the urine GAA/creatinine ratio, which could prevent a child from being diagnosed with and treated for a creatine deficiency syndrome. An increase in blood NGAL also occurred, which could lead to a misdiagnosis of acute kidney failure. The level of serum HE4 rose significantly as well, which could interfere with ovarian cancer management.

“The majority of the diagnostic disease markers in blood and urine investigated in this cohort were influenced by kidney function,” said Mørkrid. “Urine GAA/creatinine level could easily be shifted below the diagnostic limit for screening of [CDS]. A small change in GFR could increase the level of serum HE4 above the reference limit regardless of age. A considerable increase in serum NGAL levels was observed with decreasing kidney function. This must be taken into account when interpreting test results.”