Systemic Causes of Pruritus (Itching)

The main systemic causes of itching are:

Cholestasis
Uremia
Pregnancy-related problems
Lymphoproliferative (especially systemic mastocytosis) and hematopoietic disorders, including iron deficiency anemia
Endocrinal problems such as hypothyroidism and diabetes mellitus
Drug side effects, such as opioids and drugs which cause cholestasis.
Allergic reactions

Therefore, in the absence of primary skin findings, a basic workup for itching might include:

CBC with differential, peripheral blood smear, iron, total iron-binding capacity, serumferritin
- If polycythemia is found, order erythropoietin level and PCR for JAK2 mutation
Liver chemistry studies
Serum electrolytes and glucose
TSH
Pregnancy testing

Symptomatic treatment is with antihistamines, topical or oral glucocorticoids, antipruritic lotions and emollients. (Habif, p. 595). “Intense unremitting itching unresponsive to prednisone suggests scabies or dermatitis herpetiformis,” (id at 368), so, in appropriate settings, ask these patients about gastrointestinal symptoms and about close contacts with similar symptoms.

References

Habif, Thomas P. Skin Disease, Diagnosis and Treatment (2011, reviewed here)
The Merck Manual for Health Care Professionals (accessed on 1/29/2013)

Posted

30 January, 2013

Dermatology, Internal Medicine

Mark Yoffe, MD

Tags:

Dermatitis herpetiformis, Differential diagnosis of pruritus, Workup for itching

Comments

2 responses to “Systemic Causes of Pruritus (Itching)”

Sonya D

30 January, 2013

You can also think about medication side effects, such as seen with opioids.

Reply
1. Mark Yoffe MD
  
  30 January, 2013
  
  Thank you, Dr. Sonya D., for your comment.
  
  I’ve updated the post accordingly!
  
  Reply