Endocrine disorders in a patient with a suspicion of a mitochondrial disease, MELAS syndrome - a case report and literature review.

MELAS syndrome (mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes) is a genetically determined disease caused by mutations in mitochondrial DNA. We present a girl who was suspected of MELAS syndrome during the diagnostic evaluation of short stature. The patient suffered from symptoms potentially indicating mitochondrial disease, such as muscular weakness, cranial nerve VI palsy, headaches, retinitis pigmentosa, sensory-neural hearing loss, and elevated lactic acid. T2-weighted brain MRI showed hyperintense lesions in the white matter. Muscular biopsy revealed ragged red fibres. Genetic evaluation did not detect the most common mutations in the MT-TL1 gene and MT-ND5 gene. Endocrine tests led to the confirmation of growth hormone deficiency, and so replacement treatment was started. After 1 year of recombinant growth hormone therapy the patient was diagnosed with diabetes. At the age of 14 years the LH-RH test showed prepubertal values. Endocrine disorders may be one of the first manifestations of MELAS syndrome. In differential diagnosis of short stature, less common causes, such as mitochondrial diseases, should be taken into consideration.