Hypertension Blog

Although blood tests aren’t used to detect hypertension, they are useful for identifying the effects of hypertension and the causes of secondary hypertension. They can also help in monitoring a patient’s response to hypertensive treatment.

Electrolyte Levels

Serum electrolyte testing is used to determine the body’s homeostatic status. For a patient with known hypertension, serum electrolyte levels­specifically sodium and potassium levels-can help identify complications arising from hypertension and its treatment. Serum electrolyte testing may also help identify disorders causing secondary hypertension, such as hyperaldosteronism, which is characterized by low serum potassiumlevels.

In many cases, physicians prescribe diuretics and angiotensin-converting enzyme (ACE) inhibitors to treat hypertension. If your patient’s treatment plan will include these drugs as well as a sodium-restricted diet, electrolyte testing should be performed before therapy begins. Also, you should monitor the patient’s electrolyte levels during therapy to help identify abnormal levels that can result in a life-threatening complication.

If a patient is scheduled for serum electrolyte testing, explain the reasons for the test and the importance of the findings. This will increase his knowledge of his hypertensive condition and help promote compliance with his medical regimen.

Test Implications

Normally, serum sodium levels range from 135 to 145 mEq/L, and serum potassium levels range from 3.5 to 5.0 mEq/L. If you note abnormal levels, verify that the patient is adhering to his medical regimen. If he’s complying, notify his physician, who may change the regimen-perhaps by adding a potassium supplement.

Abnormally high potassium levels may indicate changes in renal blood flow and electrolyte exchange in the renal tubules, requiring an adjustment in the patient’s ACE inhibitor dosage. High potassium levels also may result from treatment with potassium sparing diuretics.