30 Sep

A. Extensive fungal infection of the finger and toenails (onychomycosis) is often associated with hypothyroidism, a consequence of compromised cardiac contractility, leading to decreased blood flow to the extremities. The resulting low-oxygen state at the tips of the fingers and toes promotes fungal overgrowth.

B. Slow capillary refilling, demonstrable by applying firm finger pressure to areas of thin skin, is a manifestation of reduced cardiac inotropy. As thyroid levels decline, cardiac contractility decreases. The worse this condition is, the closer to the heart it will manifest. It usually begins in the extremities, and patient will experience cold hands and feet. By the time it manifests above the knee, the patient has quite serious circulatory compromise.

C. Poor capillary refilling, reflective of weak inotropy in the heart, leads to poor circulation at the extremities and facilitates fungal overgrowth in the nails. These signs are typical of longstanding hypothyroidism.

D. Fluid leakage into extracellular spaces, a result of reduced glycoaminoglycan production also results in a characteristic swollen, scalloped tongue, which is very common in hypothyroid people.

E. Conversion of beta-carotene to vitamin A is dependent on thyroid hormone. Thyroid deficiency will manifest as a yellowish buildup of carotene in the skin of the palms and soles. Poor circulation, also associated with hypothyroidism, facilitates fungal overgrowth between toes.

F. Thyroid hormone drives production of glycoaminoglycans, responsible for keeping water inside cells. In hypothyroidism, water tends to leak into extracellular spaces causing significant edema, easily recognized around the legs and ankles.

Photos: Roby Mitchell, MD, reproduced with permission.


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