Endocrine Abstracts

Introduction: Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes, combined together, under the name of MELAS syndrome, constitute one of the mitochondrial genetic diseases with dominant progressive neurodegenerative symptoms. Although nervous system involvement is often the first manifestation of the disease, during the course of the disorder, patient can develop a wide spectrum of endocrine disorders ranging from GH deficiency and hypoparathyroidism to diabetes.

Case study: 19-year old patient with MELAS syndrome was admitted to the Department of Endocrinology for routine check-up and evaluation of carbohydrate metabolism. He presented with standard features of the symptom like: encephalopathy, myopathy, hearing impairment, mental retardation, vision disturbances and history of seizures and stroke-like episodes. During the course of the disease he developed numerous endocrine manifestations of this mitochondrial pathology. He was diagnosed with short stature due to GH deficiency, after that, based on decreased calcium and PTH levels, hypoparathyroidism was recognized and suplementation was introduced. Later he was diagnosed with secondary adrenal insufficiency requiring hydrocortisone replacement therapy. During evaluation of delayed puberty hypogonadotropic hypogonadism was identified. Additionally the review of medical history revealed recurring episodes of hyponatremia probably due to unrecognized SIADH syndrome. During current hospital stay we evaluated the carbohydrate metabolism ruling out mitochondrial diabetes. Fasting glucose was within normal limits and HbA1c level was at 5.4%. Further diagnostic unmasked concomitant insulin resistance with HOMA-IR at 3.3. The dose of hydrocortisone was adjusted and the patient was referred to endocrine outpatient clinic for regular follow-up.

Conclusions: Endocrine dysfunctions, with many of them occurring concomitantly, complicating the course of the disease, are an important aspect of mitochondrial diseases, especially in patients with MELAS. Mitochondrial diabetes is hypothesized to occur as a result of insulin deficiency rather than insulin resistance, however, in some patients, the second mechanism may also play a crucial role