Endocrine manifestations and long-term outcomes of patients with mitochondrial diseases.

Background: Endocrine dysfunctions are commonly associated with mitochondrial diseases. This study aimed to investigate clinical characteristics and outcomes of endocrine manifestations in patients with mitochondrial diseases.

Methods: This study included 54 patients from 47 families with mitochondrial diseases who were genetically confirmed; 49 patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), four with Pearson syndrome, and one with Kearns-Sayre syndrome (KSS). Clinical and endocrine findings were retrospectively reviewed.

Results: The median age at diagnosis was 18.5 years (range, 0.1 - 49 years). In 49 patients with MELAS, the mean height and weight standard deviation scores were - 2.0 ± 1.3 and - 2.6 ± 1.6, respectively, with 44.9% (n = 22) of the patients exhibiting short stature at diagnosis. Twenty-three (46.9%) patients with MELAS were diagnosed with diabetes mellitus (DM) at a median age of 26 years (range, 12 - 50 years). Interestingly, papillary thyroid cancer was observed in 10.2% of patients (n = 5) with MELAS at a mean age of 34.1 ± 6.9 years. One patient with MELAS and one with KSS exhibited hypoparathyroidism. Patients with Pearson syndrome and KSS exhibited more severe short stature. Adrenal insufficiency was noted in 50% of the patients with Pearson syndrome.

Conclusions: In 20% of patients with MELAS, endocrine dysfunctions including having a short stature, DM, and hypoparathyroidism preceded the onset of neurological manifestations. Papillary thyroid cancer occurred in 10% of patients with MELAS. Patients with Pearson syndrome and KSS showed profound growth retardation and multisystem dysfunctions, such as chronic kidney disease and neurological defects, which contributed to increased mortality.