What laboratory tests are recommended for a 15-year-old female with chronic pruritic (itchy) palmar erythema (redness) of 1 year duration?

Laboratory Evaluation for a 15-Year-Old Female with Red Itchy Palms

The recommended laboratory tests for a 15-year-old female with red itchy palms for 1 year should include a full blood count, liver function tests, ferritin levels, and urea and electrolytes to identify potential underlying causes. 1

Initial Laboratory Workup

First-line Tests:

• Complete blood count with differential
  • To detect eosinophilia (parasitic infections) or leukopenia (autoimmune conditions)
  • To evaluate for polycythemia
• Liver function tests
  • AST, ALT, bilirubin, alkaline phosphatase
  • Consider bile acids if liver tests are abnormal
• Ferritin levels
  • To assess for iron deficiency or iron overload
• Urea and electrolytes
  • To evaluate renal function
• C-reactive protein/ESR
  • To detect inflammatory conditions

Second-line Tests (Based on Clinical Suspicion):

• Thyroid function tests and thyroid autoantibodies
  • Especially if other symptoms of thyroid dysfunction are present
• Total IgE level
  • May help identify allergic or autoimmune causes
• JAK2 V617F mutation analysis
  • If polycythemia is suspected based on elevated hemoglobin/hematocrit

Clinical Context and Differential Diagnosis

Palmar erythema with pruritus in a 15-year-old female could be related to several conditions:

1. Liver disorders: Palmar erythema occurs in 23% of patients with liver cirrhosis 2. Consider hepatitis serology if liver function tests are abnormal.

2. Autoimmune conditions: Palmar erythema is reported in >60% of patients with rheumatoid arthritis 2. Consider ANA, RF if joint symptoms are present.

3. Endocrine disorders:

   • Thyrotoxicosis (up to 18% of patients) 2
   • Diabetes mellitus (4.1% of patients) 2

4. Dermatological conditions:

   • Chronic urticaria - consider autologous serum skin test in specialized centers 3
   • Contact dermatitis from frequent hand sanitizer use 4

5. Intrahepatic cholestasis: Though typically seen in pregnancy, adolescent females can develop cholestatic conditions 3

Important Considerations

• Avoid extensive malignancy workup unless there are specific concerning features 3, 1
• Do not routinely perform endocrine investigations unless clinical features suggest endocrinopathy 3, 1
• Consider environmental exposures (hand sanitizers, soaps, chemicals) as potential causes 4
• The majority of causes can often be diagnosed from history and physical examination alone 5

When to Consider Additional Testing

• If initial laboratory tests are normal but symptoms persist, consider:
  • Skin biopsy (if lesions are present)
  • Referral to dermatology for specialized testing
  • Evaluation for neuropathic causes if other neurological symptoms are present

Pitfalls to Avoid

1. Over-investigation without clinical indication
2. Failure to consider common environmental exposures
3. Missing systemic diseases that may present with isolated palmar symptoms
4. Not considering age-appropriate conditions (adolescent-specific disorders)

Remember that palmar erythema can be physiologic or pathologic, and the chronic nature of the symptoms (1 year duration) suggests a need for thorough but targeted investigation to identify any underlying systemic condition.