His rehabilitation continued with gradual increases in activity level and improvement in athletic performance. Previous musculoskeletal symptoms and fatigue did not recur. He has since attained personal best race times and has had his best triathlon season. Disease Assessment Hypothyroidism, a disorder commonly seen in primary care medicine, is a metabolic state caused by thyroid hormone deficiency. Once suspected, the diagnosis is easily established in all but rare cases by the history, physical examination, and laboratory findings.
Hypothyroidism can be primary or secondary.
In primary hypothyroidism, the hormone deficiency results from a disease or process within the thyroid gland. Hashimoto's disease, an immune-mediated thyroiditis, is an example. In this condition, blockade of thyroid TSH-receptors results in decreased T4 production. Secondary hypothyroidism, which is rare, is characterized by measurably decreased TSH secretion secondary to hypothalamic-pituitary axis impairment. Pituitary adenoma is the most common cause.