Changes

===Antidiuretic Hormone (ADH)===

===Antidiuretic Hormone (ADH)===

In heart failure, there are increased circulating levels of ADH. ADH is usually involved in regulation of osmolality and plays less of a role in regulation of circulating fluid volume. The stimulus for this 'non-osmotic' release of ADH is probably a marked drop in blood pressure. Therefore increased ADH occurs in late stage or severe heart failure.

Release of ADH from the posterior pituitary gland increases absorption of free water in the collecting duct of the nephron. ADH is usually involved in regulation of osmolality and plays less of a role in regulation of circulating fluid volume. In heart failure, there are increased circulating levels of ADH. The stimulus for this 'non-osmotic' release of ADH is probably a marked drop in blood pressure. Therefore increased ADH occurs in late stage or severe heart failure.

 

Excess ADH leads to fluid retention, contributing to congestive heart failure, and dilutes total body sodium and chloride leading to hypo-osmolarity. The finding of hyponatraemia and hypochloraemia on blood tests from patients with cardiac disease indicate an advanced stage of disease. Dilutional hyponatraemia (excess free water, rather than a reduction in sodium) is a poor prognostic sign.

== Classification  ==

== Classification  ==