What is the primary consequence of a deficit in T3 and T4 levels in hypothyroidism?

A deficit in T3 and T4 levels in hypothyroidism leads to a slowed metabolism. Thyroid hormones, particularly triiodothyronine (T3) and thyroxine (T4), play a crucial role in regulating the body's metabolic rate. When these hormones are deficient, as seen in hypothyroidism, the body's metabolic processes slow down significantly. This slowdown affects various body functions, including energy production, heat generation, and the metabolism of carbohydrates, proteins, and fats.

As a result of this reduced metabolic rate, individuals often experience a range of symptoms associated with hypothyroidism. These symptoms can include fatigue, weight gain, and a general decrease in energy levels, which are all manifestations of the body's decreased metabolic activity. Hence, in the context of hypothyroidism, the primary consequence of low T3 and T4 levels is indeed a slowed metabolism.