Intro: UP also known as chronic kidney disease associated pruritus (CKD-aP) is a chronic itching in patients suffering from chronic kidney diseases and one-third of patients undergoing dialysis (irrespective of the type of dialysis whether it is peritoneal or hemodialysis) develop this condition. Itching could be mild and localized or could spread to various areas with more intensity that could result in depression, sleep disturbances, negative impact on quality of life and mortality.
Etiology: the etiology of UP is not completely understood but studies support that people having this problem are usually male and have a high concentration of blood urea nitrogen, high levels of phosphates, hypermagnesemia, hypercalcemia, and secondary hyperparathyroidism. Medications like ACE inhibitors can also play a contributing factor in developing UP.
Pathophysiology: being a common complication of end stage renal disease, its pathogenesis is multifactorial. Uremia related abnormalities, systemic inflammation, uremic toxin accumulation, co-morbidities like diabetes or viral hepatitis can act as the triggers.
Opioid hypothesis define that UP is caused as a consequence of imbalance in the expression of mu and kappa receptors. Mu receptor agonists are capable of producing pruritus via mu receptor induction and kappa receptor blockade. Increased serum betaendorphin to dynorphin ratio seen in hemodialysis can lead to further changes in endogenous opioidergic systems.
Clinical presentation: include excoriations (due to scratching), impetigo (in some cases), prurigo lesions and lichenification. The itching has a symmetric distribution with worsened intensity at night. In certain patients it is severe during or after dialysis. Areas like head, arms, back, and abdomen get affected. Agitation and depression is commonly seen in such patients.
Diagnosis: other etiologies need to be ruled out first. Abnormal dryness (xerosis) is usually present is patients undergoing dialysis. It occurs due to the impaired secretions, atrophy of sweat glands and reduced hydration. So, Xerosis needs to be resolved before the final conclusion of UP being the cause of itching in renal disease.
Treatment: pharmacotherapeutic management is dependent on the severity of the patient’s symptoms and whether the patient is responsive to the initial therapies or not.
Therapies are classified according to the topical, systemic or dialysis related. First choice to start the treatment is with topical emollients and gabapentin and then moving up to systemic drugs.
|Agent||Dose||Common side effects|
|Capsaicin||0.025% ointment topical qid||Burning, redness, stinging|
|Tacrolimus||0.03% and 0.1% ointment topical bid for 6 weeks||Vomiting, erythema, pruritus|
|Gabapentin||400mg twice weekly||Dizziness, nausea, weight gain, somnolence|
|Pregabalin||25-75 mg/day||Dizziness, nausea, weight gain, somnolence|
|Sertraline||50mg once daily||Nausea/vomiting, fatigue, constipation, diarrhea|
|Glucocorticoids||0.5-2 mg/kg (actual body weight)||
Edema, hyperglycemia, osteoporosis, hypertension,
|Omega 3 fatty acids||1 g tid for 20 days||Altered taste, burping, indigestion|