Norwegian researchers have determined that a number of diagnostic nephrological tests have been found to be less accurate when performed in pediatric patients with impaired kidney function, according to a study published in the American Association for Clinical Chemistry’s Journal of Applied Laboratory Medicine.
These study findings indicate that healthcare providers need to examine patient kidney function when interpreting clinical test results for certain conditions to ensure that pediatric patients receive the correct diagnoses and treatments.
These researchers, led by Lars Mørkrid, MD, PhD, of Oslo University Hospital in Oslo, Norway, explained that many different patient groups can develop impaired kidney function. This impairment can result from an actual kidney disorder, but can also be caused by common treatments that stress the kidneys, such as chemotherapy. He explained that because the kidneys filter some of the body’s molecules that indicate the presence of disease, known as biomarkers, it is suspected that impaired kidney function could lead to decreased accuracy of diagnostic tests that measure these biomarkers. If this is the case, healthcare providers need to know which clinical tests are affected by impaired kidney function so that they can interpret these test results accurately. Otherwise, patients could be misdiagnosed, under- or over-treated, or monitored improperly due to clinicians thinking that patients are more or less sick than they actually are.
In this study, Dr. Mørkrid and colleagues have found that impaired kidney function can affect test results for the developmental disorders known as creatine deficiency syndromes, for acute kidney failure, and for ovarian cancer.
To confirm this effect, 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. They evaluated participant kidney function using measured glomerular filtration rate (mGFR). When the mGFR level decreased, indicating reduced kidney function, 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 Dr. 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.”