What blood tests are necessary before starting Risperidone (risperidone) in a patient with treatment-resistant bipolar disorder or schizophrenia, and how often should they be repeated?

Blood Tests Required Before Starting Risperidone and Monitoring Frequency

Before initiating risperidone, obtain baseline fasting glucose (or HbA1c), lipid panel, complete blood count, renal and liver function tests, and ECG; repeat metabolic monitoring (glucose and lipids) at 3 months, then annually, with more frequent testing if risk factors are present. 1, 2

Pre-Treatment Laboratory Assessment

The following baseline tests should be obtained before starting risperidone:

• Fasting blood glucose or HbA1c - Essential for establishing baseline glycemic status 2
• Fasting lipid panel (total cholesterol, triglycerides) - Required to monitor for dyslipidemia risk 2
• Complete blood count (CBC) - Baseline hematological assessment 1
• Renal function tests (urea and electrolytes) - To assess kidney function 1
• Liver function tests - Baseline hepatic assessment 1
• ECG - May be indicated depending on patient risk factors 1
• Baseline movement assessment - Document any pre-existing abnormal movements to avoid misattribution to medication 1

Additional baseline measurements should include BMI, waist circumference, and blood pressure 3.

Monitoring Schedule During Treatment

Metabolic Monitoring Frequency

For patients with established diabetes:

• Monitor glucose control regularly throughout treatment 2

For patients with diabetes risk factors (obesity, family history):

• Fasting blood glucose testing at baseline and periodically during treatment 2

For all patients:

• Monitor for hyperglycemia symptoms (polydipsia, polyuria, polyphagia, weakness) at each visit 2
• If hyperglycemia symptoms develop, obtain fasting blood glucose immediately 2

Structured Monitoring Timeline

• 3 months: Repeat fasting glucose, lipid panel, waist circumference 3, 2
• 6 months: Waist circumference 3
• Annually: Comprehensive metabolic panel including glucose, lipids, BMI, blood pressure 3

Critical Clinical Context

The FDA label emphasizes that risperidone, like other atypical antipsychotics, carries risk of metabolic changes including hyperglycemia, dyslipidemia, and weight gain 2. In pooled data from controlled trials, risperidone showed mean glucose increases of +0.8 to +0.6 mg/dL over 3-8 weeks, with 0.4-0.6% of patients shifting from normal to diabetic range 2.

Important Caveats

• No routine blood level monitoring is required for risperidone (unlike clozapine, which requires specific therapeutic level monitoring) 3
• The relationship between antipsychotic use and glucose abnormalities is complicated by increased baseline diabetes risk in patients with schizophrenia 2
• Some cases of hyperglycemia resolved upon discontinuation of risperidone, while others required continued anti-diabetic treatment 2

Movement Disorder Monitoring

While not blood tests, extrapyramidal symptom monitoring is critical, as risperidone has the highest risk of EPS among atypical antipsychotics, occurring even at doses as low as 2 mg/day 1. Document baseline abnormal movements before treatment initiation 1.

Special Population Considerations

Elderly patients with dementia: More intensive monitoring may be warranted given increased sensitivity to metabolic and neurological effects at lower doses 1

Pediatric patients: The same metabolic monitoring schedule applies, with particular attention to growth parameters 2