Relationship Between Fatty Degeneration of Thigh Muscles and Vitamin D Status in the Elderly: A Preliminary MRI Study

OBJECTIVE. The purpose of this study was to study the relationship between fatty degeneration of thigh muscles and vitamin D status in elderly adults. SUBJECTS AND METHODS. For six months, 121 patients 65 years old or older were evaluated. Myopathy, muscular impairment, and conditions influencing vitamin D status other than diet and sunlight were exclusion criteria. Twenty patients (10 men and 10 women; mean age, 77.6 years) underwent MRI. Thigh muscles were scanned from the hip to the knee with T1- and T2-weighted spin-echo sequences. Skeletal muscles were evaluated for fatty degeneration and atrophy from grade 0 to 3 (grade 0 = normal appearance, grade 3 = severe changes). The relationship between muscular fatty degeneration, 25-hydroxyvitamin D (25-OHD) levels, and scores on Tinetti scales for balance and gait were examined. RESULTS. In the evaluation of the extensor muscles for fatty degeneration and atrophy, grade 0 was present in three patients (15%), grade 1 in 11 (55%), and grade 2 in six (30%). In the flexor muscles, grade 0 was found in one patient (5%), grade 1 in five (25%), and grade 2 in 14 (70%); grade 3 changes were not seen. Muscular fatty degeneration negatively correlated with 25-OHD levels (r = -0.50, p < 0.01) and the Tinetti scores (balance: r = -0.40, p < 0.05; gait: r = -0.50, p < 0.05). In 11 vitamin D-deficient patients (55%), there was selective complete atrophy of at least one thigh muscle. The gracilis and sartorius muscles were spared. CONCLUSION. In elderly adults, fatty degeneration of thigh muscles was associated with vitamin D deficiency and impaired balance and gait. Selective complete fatty degeneration of single muscles was observed.