Research finds diagnostic tests to be less accurate for children with impaired kidney function

Breaking research published today in AACC's Journal of Applied Laboratory Medicine reveals that a number of diagnostic tests are less accurate when performed in pediatric patients with impaired kidney function. These findings show that healthcare providers should assess patient kidney function when interpreting clinical test results for certain conditions to ensure that patients receive the correct diagnoses and treatments.

Many different patient groups can develop impaired kidney function-;it can result from an actual kidney disorder, but can also be caused by common treatments that stress the kidneys such as chemotherapy. 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 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 correctly. 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, scientists led by Lars Mørkrid, MD, PhD, of Oslo University Hospital, Norway, have found that impaired kidney function impacts tests for the developmental disorders known as creatine deficiency syndromes, for acute kidney failure, and for 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 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 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."