Should an Oral Glucose Challenge Test (OGCT) be performed in a patient with colestasis of pregnancy?

Oral Glucose Challenge Test in Cholestasis of Pregnancy

Yes, patients with cholestasis of pregnancy should undergo an Oral Glucose Challenge Test (OGCT) as part of their prenatal care due to evidence suggesting altered carbohydrate metabolism in these patients.

Rationale for OGCT in Cholestasis of Pregnancy

Research has demonstrated that women with intrahepatic cholestasis of pregnancy show alterations in glucose metabolism, including:

• Higher glucose concentrations 2 hours after meals compared to healthy pregnant women 1
• Consistently higher glucose concentrations after glucose loading 1
• Abnormal 24-hour glycemia profiles 1

These findings suggest that cholestasis may be associated with changes in carbohydrate metabolism that could increase the risk of gestational diabetes mellitus (GDM).

Recommended Screening Approach

Timing of Screening

• For women with cholestasis of pregnancy, follow the standard GDM screening timeline:
  • Initial screening at 24-28 weeks gestation for average-risk women 2, 3
  • Earlier screening (at first prenatal visit) if other high-risk factors are present 2, 3

Preferred Screening Method

• Two-step approach (most commonly used in the US):

  1. Initial 50-gram glucose challenge test (GCT/OGCT) - non-fasting
  2. If abnormal (≥140 mg/dL), proceed to diagnostic 100-gram OGTT 2, 3

• Alternatively, a one-step approach with 75-gram OGTT can be used, particularly in high-risk populations 2

Diagnostic Criteria

Two-Step Approach

• OGCT: Abnormal if 1-hour glucose ≥140 mg/dL (7.8 mmol/L) 2, 3
• Diagnostic 100-gram OGTT: GDM diagnosed when two or more values meet or exceed:
  • Fasting: 95 mg/dL (5.3 mmol/L)
  • 1-hour: 180 mg/dL (10.0 mmol/L)
  • 2-hour: 155 mg/dL (8.6 mmol/L)
  • 3-hour: 140 mg/dL (7.8 mmol/L) 2

Clinical Considerations

• The prevalence of GDM ranges from 1-14% depending on the population studied 2
• An abnormal GCT followed by a normal OGTT still indicates metabolic dysfunction that may persist postpartum 4
• Universal screening detects more cases of GDM than risk-factor based screening 5

Importance of Screening

Screening for GDM in women with cholestasis is important because:

1. Early detection allows for appropriate management to reduce complications
2. Women with GDM have a 10-fold increased risk of developing type 2 diabetes later in life 2
3. The absolute risk of developing type 2 diabetes increases linearly through a woman's lifetime 2

Follow-up After Pregnancy

For women diagnosed with GDM:

• Screen for persistent diabetes at 4-12 weeks postpartum with a 75-gram OGTT 2, 3
• Continue lifelong screening for diabetes at least every 3 years 2, 3

Potential Pitfalls

• Failing to screen women with cholestasis who may have altered glucose metabolism
• Using inappropriate diagnostic thresholds
• Poor follow-up rates for postpartum testing
• Discontinuing long-term surveillance for women with history of GDM 3

Given the evidence of altered glucose metabolism in cholestasis of pregnancy and the importance of detecting GDM, performing an OGCT in these patients is a prudent clinical approach.