Blood chemistry tests
When is this exam indicated?
In the specific scope of cardiovascular disease and heart failure, hematochemical tests are useful for differential diagnosis with other diseases and for monitoring the patient with decompensation.
They may also have prognostic value. Specifically:
- anemia may intensify pre-existing heart failure;
- high hematocrit may point to pulmonary disease, cyanotic congenital heart disease or pulmonary arteriovenous malformation;
- measurement of urea and serum creatinine is essential for differential diagnosis with renal failure. Untreated heart failure is rarely associated with significant electrolyte alterations, which are very common among patients taking diuretics. In case decompensation is associated already in the early stages with renal dysfunction and hyposodiemia, the prognosis is worse;
- increased liver enzymes may be consequent to liver congestion;
- assessment of proteinuria and glycosuria are warning signs of a renal problem that may complicate ongoing decompensation;
- hyperthyroidism and hypothyroidism may be separate causes of heart failure and complications.
Therefore, thyroid function should always be monitored through measurements of its circulating hormones.
How is it performed?
The tests contained in the hematochemical checkup are non-invasive checks, performed through a simple blood draw usually in the morning on an empty stomach. Apart from a slight pinch as the needle enters the arm, blood tests are not dangerous or painful.