Lab Tests for Monitoring Drug Therapy

Laboratory Tests for Monitoring Drug Therapy

Laboratory tests are essential tools in monitoring drug therapy, allowing healthcare providers to make informed decisions about patient treatment. It is crucial to remember that laboratory tests should only be ordered if the results will have a direct impact on patient treatment decisions. This approach ensures that healthcare providers are using resources efficiently and minimizing unnecessary testing.

Reference Range and Factors Affecting It

The reference range is a statistically derived numeric range obtained from testing healthy individuals. This range serves as a benchmark for comparing patient results. However, it is essential to consider factors that can affect the reference range, including age, sex, and race. These factors can influence laboratory results, and healthcare providers must take them into account when interpreting test results.

Treating the Patient, Not the Lab Value

It is vital to remember that laboratory tests are only a tool to aid in patient care. Healthcare providers should focus on treating the patient, not the lab value. This approach recognizes that laboratory results are only one aspect of patient care and that clinical significance should be the primary consideration.

Screening Tests for Untreated Conditions

Screening tests play a critical role in identifying untreated conditions, allowing for early intervention and prevention of complications.

Type 2 Diabetes

Screening for Type 2 diabetes is recommended for individuals over 40 years old, with a frequency of every three years. However, patients with risk factors such as vascular disease, hypertension, dyslipidemia, gestational diabetes, obesity, or a family history of diabetes may require earlier and more frequent screening.

Prediabetes and Impaired Glucose Tolerance

Prediabetes, also known as impaired glucose tolerance or impaired fasting glucose, increases the risk of developing diabetes and its complications. A 75g oral glucose tolerance test (OGTT) is indicated if fasting blood glucose (FBG) is between 6.1-6.9 mmol/L or if it is ≥ 6.5%.

Diagnostic Criteria for Diabetes and Prediabetes

The diagnostic criteria for diabetes and prediabetes are based on fasting plasma glucose levels and 2-hour glucose levels during the 75g OGTT.

Fasting Plasma Glucose (mmol/L)

The diagnostic criteria for fasting plasma glucose levels are:

• Normal: < 6.1
• Impaired Fasting Glucose (IFG): 6.1-6.9
• Diabetes: ≥ 7.0

2-Hour Glucose Level during 75g OGTT (mmol/L)

The diagnostic criteria for 2-hour glucose levels during the 75g OGTT are:

• Normal: < 7.8
• Impaired Glucose Tolerance (IGT): ≥ 7.8 and < 11.1
• Diabetes: ≥ 11.1

Dyslipidemia

Dyslipidemia, or abnormal levels of lipids in the blood, is a major risk factor for cardiovascular disease. Lipid tests are used for screening and risk stratification for cardiovascular disease.

Lipid Tests

The fasting lipid panel typically includes:

• Total Cholesterol (TC)
• High-Density Lipoprotein Cholesterol (HDL-C)
• Low-Density Lipoprotein Cholesterol (LDL-C)
• Triglycerides (TG)
• TC:HDL ratio

Screening Recommendations

Screening for dyslipidemia is recommended for:

• Men ≥ 40 and women ≥ 50
• Patients with cardiac risk factors, regardless of age:
  • Diabetes
  • Hypertension
  • Current smokers
  • Obesity
  • Family history of premature CAD
  • CKD

Lipid Panel and Fasting

It is essential to perform the lipid panel while fasting, as food intake can affect lipid levels. Patients should refrain from eating for at least 12 hours (9 hours for diabetics) before drawing a blood sample.

Treatment Recommendations and Targets

Treatment recommendations