Among the conditions in which circulating GDF15 levels are highly elevated are mitochondrial disorders, where early skeletal muscle fatigue is a key symptom.
Circulating growth differentiation factor 15 measurement is a superior biomarker with high sensitivity and specificity, which can be used as a non-invasive test to screen for primary mitochondrial diseases and dysmetabolic myopathy with associated mitochondrial dysfunction in susceptible individuals.
Thus, the overall positive and negative predictive values were not acceptable for these measurements to be used as diagnostic tests for mitochondrial diseases (FGF-21 positive predictive value [PPV] = 34%, negative predictive value [NPV] = 73%; GDF-15 PPV = 47%, NPV = 28%).
We analyzed serum FGF21 (S-FGF21) and GDF15 from patients with (1) mitochondrial diseases and (2) nonmitochondrial disorders partially overlapping with mitochondrial disorder phenotypes.
Therefore, the protocol for a future clinical study of SP therapy in this patient population needs to include plasma and lateral ventricular lactate, the L/P ratio, and serum GDF15 as diagnostic indicators, and exclude patients with end-stage mitochondrial disease.
In the present review, a literature research, using PubMed database about the reliability of FGF-21 as a biomarker for mitochondrial disorders and its comparison with GDF-15 has been performed.