Analyze Insights

Plasma Copeptin Levels: a Biomarker of Renal Function

Patient Using Mobilephone at Dialysis CenterCopeptin is the C-terminal portion of the precursor of arginine vasopressin, a hormone involved in cyst growth in kidneys. This peptide is involved in renal pathways and function, and it is elevated in patients with the inherited autosomal dominant polycystic kidney disease, ADPKD. ADPKD often leads to the formation of cysts, as well as end stage kidney disease.

In patients with ADPKD, a high copeptin concentration is associated with accelerated growth of the total kidney volume, TKV, which leads to a decrease in measurable glomerular filtration rate, GFR, a test performed to evaluate how efficiently a kidney is working. Copeptin is a major risk factor for renal morbidity in ADPKD and its measurement could serve as a useful prognosticator in patients with this disorder.

A recent study from the Department of Nephrology at The University of Groningen, in the Netherlands, investigated the increase in copeptin concentration in patients with ADPKD. Copeptin levels were assessed in living kidney donors, measured both before and after donation, and in patients with ADPKD. GFR was also determined in both groups and patients with ADPKD underwent a standardized abdominal MRI protocol as well. Analyze software was used to unlock information from MRI scans as it has the advantage of a superior soft-tissue contrast, which provides a powerful tool in the detection and characterization of renal lesions. Analyze software was also utilized to measure the TKV on the T2-weighted coronal images.

As predicted, copeptin levels were significantly higher in patients with ADPKD compared with donors both pre- and post- donation. Donors showed different results: despite a remarkable fall in GFR after donation, copeptin levels pre- and post- donation did not significantly change.

The researchers hyphotesized that elevated copeptin levels could result from decreased kidney clearance or as a compensation for impared concentrating capacity, such as an increase in arginine vasopressin to maintain water homeostasis. Because no elevation in copeptin was observed in healthy kidney donors, despite a considerable decrease in GFR after donation, it is unlikely that renal clearance holds a predominant role in determining copeptin levels.

Therefore, these elevated levels are considered a result of impaired urine concentrating capacities caused by cyst-induced abnormalities in the medullary osmolar gradient, which is responsible for the final concentration of urine collected in the ducts.

Due to the increasing demand for donor kidneys and the relative shortage of cadaver kidneys, the importance of living donors is increasing. In recent years, progress has been made in the use of MRI for the evaluation of renal function. Through MRI scans and vigilant testing, measurement of renal function may be used as an indicator of severity of disease and can direct therapy of the kidney.

Tags: