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.