Evaluating Intact Parathyroid Hormone for Differentiating Chronic Kidney Disease From Acute Kidney Injury in...

Background: Distinguishing between chronic kidney disease (CKD) and acute kidney injury (AKI) in hospitalized patients without prior medical records is a common yet critical challenge, particularly in emergency settings, with direct implications for clinical decision-making and patient outcomes. This study aimed to evaluate the diagnostic performance of intact parathyroid hormone (iPTH) in differentiating AKI from CKD in adults admitted to the hospital with kidney dysfunction.

This retrospective cohort study included hospitalized adults (aged 18 years and older) with serum creatinine levels ≥1.3 mg/dL, no prior history of CKD, and available iPTH measurements, from January 2015 to July 2023. Two nephrologists, blinded to the iPTH results, independently classified patients as having CKD or AKI. In cases of disagreement, a third nephrologist provided the final classification. The diagnostic performance of iPTH was assessed using receiver operating characteristic (ROC) curves, and optimal cut-off values were determined using Bayes' theorem.

A total of 200 patients were included (107 with AKI and 93 with CKD). The area under the ROC curve for iPTH in distinguishing AKI from CKD was 0.81 (95% CI 0.70-.090). Cut-off values of 125, 132, and 170 pg/mL yielded sensitivities of 75.3%, 71%, and 57%, and specificities of 73.8%, 77.6%, and 88.8%, respectively. Values ≥170 pg/mL were most specific for confirming CKD, while levels <125 pg/mL favored AKI.

iPTH effectively distinguishes AKI from CKD. A cut-off of 170 picograms per milliliter is optimal for confirming CKD, while values below 125 picograms per milliliter are useful for ruling it out.