1. Mast cells.
Mast cells of the skin are very close to the terminal neurons of C-fibers and are closely related to pruritus. Mast cells secrete pruritogenic substances such as histamine, protease, interleukin-2 (IL-2), and tumor necrosis factor. The number of mast cells and the level of histamine are higher in hemodialysis patients with pruritus than in patients without pruritus. Histamine causes pruritus by directly stimulating HI receptors in nerve endings.
Protease, in turn, stimulates the release of substance P from mast cells, which increases the release of TNF-& through the binding of substance P to NKI receptors.
2. Secondary hyperparathyroidism.
In patients after parathyroidectomy, skin itching is significantly relieved or disappears. Some studies have found that skin itching and PTH levels are related, so it is presumed that secondary hyperparathyroidism is a cause of skin scratching.
3. Endogenous opioid substances.
Endogenous opioid substances play an important role in both neurotransmission and modulation of itching. Stimulation of opioid-like receptors in the skin and central nervous system can, cause pruritus, while their antagonists can relieve skin itching in hemodialysis patients.
4. Dry skin syndrome.
Dry skin syndrome is the most common skin lesion in uremic hemodialysis patients, accounting for about 50%-85% of cases, which may be caused by atrophy and exocrine dysfunction of sebaceous and sweat glands, elevation of pH in skin stratum corneum, and elevation of vitamin A concentration in epidermis.
Treatment.
1.Suppression of secondary hyperparathyroidism
(1) Apply 2-4ug of osteopontin, orally twice a week.
(2) If the effect is not good, subtotal parathyroidectomy is feasible.
2.Antihistamines such as paracetamol, metformin
3.Ultraviolet light therapy (UV.)
The current study shows that UVB therapy has a positive effect on pruritus in hemodialysis patients. the wavelength of UVB should be 290-320 nm. the specific mechanism is not clear. The number of mast cells in hemodialysis patients with combined pruritus is significantly higher than that in patients without pruritus, and UVB therapy can reduce the number of mast cells in patients and lead to apoptosis of mast cells. UVB therapy is commonly associated with skin redness and burning sensation, so a mask should be used to protect the head locally.
4. Hemodialysis combined with hemoperfusion.
It can significantly increase the clearance of macromolecular toxic substances in patients, thus relieving the patient’s skin itching.
5. Naltrexone.
It is an opioid receptor antagonist, as already mentioned endogenous opioid substances are a mechanism for causing itching so this drug can relieve itching. Usage: 50mg daily, 7-10 as a course of treatment. The effect is better.
6. Others.
Heparin, lidocaine, activated charcoal oral, etc., upstairs comrades have expressed, not to repeat.