Monitoring Laboratory Parameters
The frequency of laboratory follow-up depends on baseline laboratory values, associated medical problems and risk factors, and type of drugs used. If a diuretic, angiotensin-converting enzyme inhibitor, or ARB is prescribed, laboratory evaluation, which includes glucose, blood urea nitrogen, creatinine, sodium, and potassium levels, should be recorded within 2 wk. Initiation of a β-blocker, an a-blocker, or a calcium antagonist does not require frequent laboratory evaluation. A slight increase in creatinine levels is expected after administration of an angiotensin-converting enzyme inhibitor or ARB. An increase in serum creatinine of <1 mg/dL allows drug continuation, with close monitoring to confirm stabilization of renal function. A slight decrease in serum potassium and sodium is expected with diuretic use. However, these changes are mild and insignificant when a low dose of diuretic is used. Elderly women are more prone to develop diuretic-induced hyponatremia, and therefore this subgroup of patients should be closely monitored for serum electrolytes. Note that although most patients develop electrolyte disturbance during the first month of treatment, there are patients who may develop hyponatremia even after long-term use of diuretics especially when a precipitating event such as infection or diarrhea occurs. Any abnormal laboratory results observed in the first work-up, such as low levels of sodium or potassium or elevated creatinine, glucose, or lipid levels, require frequent repeated measurements until they are stabilized in the accepted range. Patients with renal failure require close monitoring of renal function and electrolytes during treatment.
Table Medical History During Follow-up
| 1. Weakness (hypotension, bradycardia from β-blockers, orfhostasis from treatment). |
| 2. Dyspnea (signs of congestive heart failure, or exacerbation of asthma in patients using P-blockers) |
| 3. Chest pain — anginal syndrome (signs of ischemic heart disease) |
| 4. Intermittent claudication, Raynaud phenomenon (side effects of P-blockers or development of peripheral vascular disease). |
| 5. Leg edema (side effect of calcium antagonists or signs of congestive heart failure) |
| 6. Bowel movements (constipation as a side effect of calcium antagonists) |
| 7. Nutritional status — assessing salt and caloric intake (to understand lack of response to treatment) |
| 8. Headache (related to hypertension or side effect of drugs) |
| 9. Sexual activity (side effect of drugs) |
| 10. Nocturia (side effect of diuretic or calcium antagonists, may guide to change treatment to a-blocker) |
| 11. Hypertrophy of the gums (side effect of calcium antagonists) |
| 12. Cough (side effect of angiotensin-converting enzyme inhibitors, or signs of congestive heart failure) |
| 13. Insomnia (a marker of depression or side effect of p-blockers) |
| 14. Snoring (a sign of sleep apnea) |
Laboratory work-up should also aim to identify worsening in other risk factors and target organ damage. Therefore, it is justified to measure fasting glucose, lipid profile, and urinalysis, including urine for microalbumin.
If the first laboratory results are normal, evaluation once a year is recommended. If glucose or lipid levels are slightly elevated, repeated evaluation is recommended.
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