hormone resistance

Picture sending text messages to someone whose phone is on silent: you keep sending, the messages arrive, but nothing happens because they aren't being read. Hormone resistance is like that — the hormone is present, sometimes in large amounts, but the target tissue can't or won't respond to its signal, so the hormone's job goes undone even though it is physically there.

The block usually lies in the receiving end: a faulty hormone receptor, a broken step in the cascade the receptor triggers inside the cell, or fewer receptors on the surface. Because the tissue acts as if the hormone were missing, the body often responds by making even more of it — so a hallmark of resistance is a high hormone level paired with signs of deficiency. This odd combination is what distinguishes resistance from simple over- or under-production.

The most common and important example is insulin resistance, where muscle, fat, and liver respond poorly to insulin; the pancreas compensates by secreting more, and blood sugar still drifts up, setting the stage for type 2 diabetes. Resistance can also be inherited and selective, as in rare syndromes of resistance to thyroid hormone or androgen, where a single receptor gene is altered.