What laboratory tests are required to monitor a patient who has been taking hydralazine (Hydralazine) 25 milligrams (mg) three times a day for two months?

From the Guidelines

For a patient who has been on hydralazine 25 mg three times daily for two months, recommended laboratory monitoring should include complete blood count (CBC), antinuclear antibody (ANA) test, and renal function tests (BUN, creatinine). These tests should be performed every 3-6 months during continued therapy. Additionally, liver function tests may be considered, though they're less critical than the other parameters. The CBC helps detect potential hydralazine-induced blood dyscrasias, particularly neutropenia. ANA testing is important because hydralazine can cause drug-induced lupus syndrome, especially with higher doses or prolonged use, as noted in the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1. Renal function monitoring is necessary as hydralazine is primarily excreted by the kidneys, and dosage adjustments may be needed in patients with impaired renal function. While the 25 mg TID dose is relatively low, reducing the risk of adverse effects, regular monitoring remains important for early detection of potential complications. Patients should also be educated about symptoms that warrant immediate medical attention, such as unexplained fever, joint pain, rash, or unusual bruising or bleeding. The importance of monitoring for drug-induced lupus-like syndrome with hydralazine is also highlighted in other guidelines, including those published in Circulation 1 and the Journal of the American College of Cardiology 1, reinforcing the need for vigilant monitoring. Furthermore, the association of hydralazine with sodium and water retention and reflex tachycardia, as well as its potential for causing drug-induced lupus-like syndrome at higher doses, underscores the importance of careful patient management, as discussed in Hypertension 1.

Some key points to consider in the management of patients on hydralazine include:

• Regular monitoring of CBC, ANA, and renal function tests
• Education on symptoms that require immediate medical attention
• Awareness of the potential for drug-induced lupus-like syndrome and other adverse effects
• Consideration of liver function tests, although they are less critical
• The need for dosage adjustments in patients with impaired renal function
• The importance of using hydralazine with a diuretic and beta blocker to mitigate its side effects, as suggested by the guidelines 1.

Given the potential risks associated with hydralazine, particularly at higher doses, it is crucial to prioritize regular monitoring and patient education to minimize morbidity, mortality, and improve quality of life.

From the FDA Drug Label

Complete blood counts and antinuclear antibody titer determinations are indicated before and periodically during prolonged therapy with hydrALAZINE even though the patient is asymptomatic These studies are also indicated if the patient develops arthralgia, fever, chest pain, continued malaise, or other unexplained signs or symptoms.

The patient should have complete blood counts and antinuclear antibody titer determinations performed periodically during prolonged therapy with hydralazine, as they have been taking it for two months.

• Complete blood counts are necessary to monitor for potential blood dyscrasias, such as reduction in hemoglobin and red cell count, leukopenia, agranulocytosis, and purpura.
• Antinuclear antibody titer determinations are necessary to monitor for potential autoimmune reactions. 2

From the Research

Laboratory Tests for Monitoring Hydralazine

To monitor a patient taking hydralazine 25 mg three times a day for two months, the following laboratory tests are required:

• Liver function tests, including:
  • Liver transaminases (AST and ALT) 3, 4, 5
  • Alkaline phosphatase 3, 4
  • Conjugated bilirubin 3, 4
• Complete blood count (CBC) to monitor for potential hematologic effects
• Renal function tests, including:
  • Creatinine 5
  • Electrolyte levels
• INR (International Normalized Ratio) to monitor for potential interactions with warfarin 5

Frequency of Laboratory Tests

The frequency of laboratory tests may vary depending on the patient's individual risk factors and medical history. However, based on the available evidence, it is recommended to:

• Monitor liver function tests regularly, ideally every 1-2 weeks, especially during the initial period of hydralazine treatment 3, 4
• Perform CBC and renal function tests periodically, ideally every 1-3 months, to monitor for potential hematologic and renal effects

Additional Considerations

• Patients taking hydralazine should be closely monitored for signs and symptoms of liver injury, such as jaundice, nausea, and vomiting 3, 4
• Hydralazine should be discontinued immediately if liver injury is suspected or confirmed 3, 4