SHBG is decreased in
**Core Concept**
Sex hormone-binding globulin (SHBG) is a protein that binds to and transports sex hormones, such as testosterone and estrogen, in the bloodstream. Its levels are influenced by various factors, including genetic, hormonal, and metabolic conditions.
**Why the Correct Answer is Right**
SHBG levels are decreased in conditions characterized by high levels of insulin, insulin resistance, and androgen excess. This is because insulin and insulin-like growth factors stimulate the production of SHBG, whereas androgens, such as testosterone, inhibit its production. In conditions like polycystic ovary syndrome (PCOS), hyperinsulinism, and obesity, the balance shifts towards androgen excess and insulin resistance, leading to decreased SHBG levels.
**Why Each Wrong Option is Incorrect**
* **Option A:** SHBG is not typically decreased in hypogonadism, as this condition is characterized by reduced sex hormone production, which would not directly affect SHBG levels.
* **Option B:** Hyperthyroidism is not directly associated with decreased SHBG levels; in fact, thyroid hormones can increase SHBG production.
* **Option C:** Liver cirrhosis can lead to increased SHBG levels due to the liver's decreased ability to metabolize and clear SHBG from the bloodstream.
**Clinical Pearl / High-Yield Fact**
Decreased SHBG levels are often seen in conditions with insulin resistance and androgen excess, making this a useful marker for identifying patients at risk for metabolic syndrome and polycystic ovary syndrome.
**Correct Answer:** D. Obesity.