What is a commonly associated symptom accompanying fatigue in patients with SIADH?

In patients with Syndrome of Inappropriate Antidiuretic Hormone secretion (SIADH), fatigue is often accompanied by several symptoms related to fluid retention and low serum sodium levels. However, muscle cramps can be a notable symptom that arises due to hyponatremia, which is a common consequence of SIADH.

When there is an excessive secretion of ADH, the kidneys retain more water, which dilutes the sodium in the bloodstream, leading to hyponatremia. This can cause a range of neurological and muscular symptoms. Fatigue may occur as a result of this electrolyte imbalance. In particular, muscle cramps can be an indication of underlying electrolyte disturbances seen in SIADH patients, stemming from the low sodium levels exacerbated by water retention.

While weight loss, increased thirst, and nausea are commonly associated with various other conditions, muscle cramps specifically correlate with the imbalances caused by fluid overload and low sodium levels, making it the most applicable option in this context.