Final answer:
In patients with congestive heart failure, B-type natriuretic peptide (BNP) levels are increased. Sodium, potassium, and creatinine levels may change due to complications or treatments but are not direct indicators of heart failure.
Step-by-step explanation:
In congestive heart failure (CHF), the blood levels of B-type natriuretic peptide (BNP) are increased. BNP is a hormone produced by the heart's ventricles and is secreted in response to stretching of the heart muscles due to increased blood volume. The primary role of BNP is to lower blood pressure and to reduce extracellular fluid volume (ECFV) by promoting sodium and water excretion by the kidneys. This action is necessary to counteract the effects of fluid overload in CHF. As for other analytes mentioned, while sodium and potassium levels can be affected in CHF due to medication use and kidney function, they do not consistently increase due to CHF alone. Similarly, creatinine levels might be altered in case of kidney disease, which can be a complication of CHF, but it is not a direct indicator of heart failure.