Медичні аспекти тривалої замісної ниркової терапії

Diet should be carefully controlled. Generally, hemodialysis patients tend to be anorexic and should be encouraged to eat a daily diet of 35 kcal/kg ideal body weight (in children, 40 to 70 kcal/kg/day depending on age and activity). Daily sodium intake should be limited to 2 g (88 mEq [88 mmol]), potassium to 2.3 g (60 mEq [60 mmol]), and phosphate to 800 to 1000 mg. Fluid intake, inclusive of the fluids contained in food, is limited to 1000 to 1500 mL/day and monitored by measuring weight gain between dialysis treatments. Patients undergoing peritoneal dialysis need a protein intake of 1.25 to 1.5 g/kg/day (compared with 1.0 to 1.2 g/kg/day in hemodialysis patients) to replace peritoneal losses (8.4 +/- 2.2 g/day). Survival is best among patients (both hemodialysis and peritoneal dialysis) who maintain a serum albumin> 3.5 g/dL (35 g/L); serum albumin is the best predictor of survival in these patients.

Клінічний калькулятор

Ideal Body Weight

The anemia that occurs in renal failure should be treated with erythropoiesis-stimulating agents (ESAs) and iron supplementation (see Anemia of Renal Disease and Anemia and coagulation disorders under Treatment of chronic kidney disease). Because the absorption of oral iron is limited, many patients require IV iron during hemodialysis. (Ferric carboxymaltose, sodium ferric gluconate, and iron sucrose are preferred to iron dextran, which has a higher incidence of anaphylaxis.) Iron stores are assessed using serum iron, total iron-binding capacity, and serum ferritin. Typically, iron stores are assessed before the start of erythropoietin therapy and thereafter every 2 to 3 months (1). Iron deficiency is the most common reason for erythropoietin resistance. However, some dialysis patients who have received multiple blood transfusions have iron overload and should not be given iron supplements.

Risk factors for coronary artery disease must be managed aggressively because many patients who require RRT have hypertension, dyslipidemia, or diabetes; smoke cigarettes; and ultimately die of cardiovascular disease (2). Continuous peritoneal dialysis is more effective than hemodialysis in removing fluid. As a result, hypertensive patients require fewer antihypertensive medications. Hypertension can also be controlled in many hemodialysis patients by filtration alone. Antihypertensive medications are required in the remainder. Treatment of dyslipidemia, diabetes management, and smoking cessation are very important.

Hyperphosphatemia, a consequence of phosphate retention due to low glomerular filtration rate (GFR), increases risk of soft-tissue calcification, especially in coronary arteries and heart valves. It also stimulates development of secondary hyperparathyroidism. Patients with hyperphosphatemia should avoid foods high in phosphorus. Pharmacologic treatment options include calcium-based phosphorus binders, non-calcium–based phosphorus binders, or inhibition of phosphorus absorption.

Calcium-based phosphorus binders include calcium carbonate taken orally 3 times a day with meals, and calcium acetate taken orally 3 times a day with meals. These are more inexpensive than the other phosphorus binders, but they can cause vascular calcification, as well as hypercalcemia.

Non-calcium–based phosphorus binders include sevelamer carbonate, lanthanum carbonate, sucroferric oxyhydroxide, or ferric citrate with each meal. Use of non-calcium–based phosphorus binders is associated with a 22% decrease in all-cause mortality when compared with use of calcium-based phosphorus binders (3). Some patients (eg, those hospitalized with acute kidney injury and very high serum phosphate concentrations) require the addition of aluminum-based phosphate binders, but these should be used as short-term medications only (eg, 1 to 2 weeks as needed) to prevent aluminum toxicity (4).

Tenapanor inhibits phosphorus absorption in the GI tract and can be used as add-on therapy for patients with inadequate response to phosphorus binders (5). Diarrhea is a potential adverse effect.

These complications often coexist as a result of impaired renal production of vitamin D and hypophosphatemia. Treatment of hypocalcemia is with calcitriol either orally or IV. Treatment can increase serum phosphate level and should be withheld until the level is normalized to avoid soft-tissue calcification. Doses are titrated to suppress parathyroid hormone (PTH) levels, usually to 150 to 600 pg/mL ([150 ng/L to 600 mg/L]; PTH reflects bone turnover better than serum calcium) (4). Oversuppression decreases bone turnover and leads to adynamic bone disease, which carries a high risk of fracture. The vitamin D analogs doxercalciferol and paricalcitol have less effect on calcium and phosphate absorption from the gut but suppress PTH equally well. Although there are early hints that these drugs may reduce mortality compared with calcitriol, later studies do not show any statistically significant difference in mortality. .

Cinacalcet, a calcimimetic medication, increases sensitivity of parathyroid calcium-sensing receptors to calcium and may also be indicated for hyperparathyroidism, but its role in routine practice has yet to be defined. Its ability to decrease PTH levels by as much as 75% may decrease the need for parathyroidectomy in these patients.

Toxicity is a risk in hemodialysis patients who are exposed to aluminum-contaminated dialysate (now uncommon) and aluminum-based phosphate binders. Manifestations are osteomalacia, microcytic anemia (iron-resistant), and probably dialysis dementia (a constellation of memory loss, dyspraxia, hallucinations, facial grimaces, myoclonus, seizures, and a characteristic electroencephalogram [EEG]).

Aluminum toxicity should be considered in patients receiving RRT who develop osteomalacia, iron-resistant microcytic anemia, or neurologic manifestations such as memory loss, dyspraxia, hallucinations, facial grimaces, myoclonus, or seizures. Diagnosis is by measurement of plasma aluminum before and 2 days after IV infusion of deferoxamine 5 mg/kg. Deferoxamine chelates aluminum, releasing it from tissues and increasing the blood level among patients with aluminum toxicity. A rise in aluminum level of ≥ 50 mcg/L suggests toxicity. Aluminum-related osteomalacia can also be diagnosed by needle biopsy of bone (requires special stains for aluminum).

Treatment is avoidance of aluminum-based binders plus IV or intraperitoneal deferoxamine.

Renal osteodystrophy is abnormal bone mineralization. It has multiple causes, including vitamin D deficiency, elevated serum phosphate, secondary hyperparathyroidism, chronic metabolic acidosis, and aluminum toxicity. Treatment is of the cause.

Vitamin deficiencies result from dialysis-related loss of water-soluble vitamins (eg, B, C, folate) and can be replenished with daily renal multivitamin supplements (eg, containing thiamin, riboflavin, niacin/niacinamide, vitamin B6, vitamin B12, folic acid, and pantothenic acid).

Calciphylaxis is a rare disorder of systemic arterial calcification causing ischemia and necrosis in localized areas of the fat and skin of the trunk, buttocks, and lower extremities. Cause is unknown, though hyperparathyroidism, vitamin D supplementation, and elevated calcium (Ca) and phosphate (PO4) levels are thought to contribute. It manifests as painful, violaceous, purpuric plaques and nodules that ulcerate, form eschars, and become infected. It is often fatal. Treatment is usually supportive. Several cases have been reported in which sodium thiosulfate given IV at the end of dialysis 3 times a week along with aggressive efforts to reduce the serum Ca × PO4 product has resulted in considerable improvement (6, 7). A recent clinical trial also suggests that vitamin K supplementation may be beneficial (8).

Calciphylaxis (Trunk)

Сховати деталі

This image shows early skin changes of ischemia and necrosis in localized areas resulting from calciphylaxis.

Image courtesy of Karen McKoy, MD.

Constipation is a minor but troubling aspect of long-term RRT and, because of resulting bowel distention, may interfere with catheter drainage in peritoneal dialysis. Many patients require osmotic (eg, sorbitol) or bulk (eg, psyllium) laxatives. Laxatives containing magnesium (eg, magnesium hydroxide) or phosphate (eg, Fleet enema) should be avoided.

1. 1. KDIGO Clinical Practice Guideline for Anemia in Chronic Kidney Disease: Diagnosis and evaluation of anemia in CKD. Kidney Int Suppl 2:288-291, 2012. doi:10.1038/kisup.2012.33

2. 2. U.S. Renal Data System (USRDS), National Institute of Diabetes and Digestive and Kidney Diseases: End Stage Renal Disease. Accessed May 14, 2024.

3. 3. Jamal SA, Vandermeer B, Raggi P, et al: Effect of calcium-based versus non-calcium-based phosphate binders on mortality in patients with chronic kidney disease: an updated systematic review and meta-analysis. Lancet 382(9900):1268-1277, 2013. doi: 10.1016/S0140-6736(13)60897-1

4. 4. KDIGO Executive Committee: KDIGO 2017 clinical practice guideline update for the diagnosis, evaluation, prevention, and treatment of chronic kidney disease—Mineral and bone disorder (CKD-MBD). Kidney Int Suppl 7(1):1-159.

5. 5. Pergola PE, Rosenbaum DP, Yang Y, et al: A randomized trial of tenapanor and phosphate binders as a dual-mechanism treatment for hyperphosphatemia in patients on maintenance dialysis (AMPLIFY). J Am Soc Nephrol 32(6):1465-1473, 2021. doi: 10.1681/ASN.2020101398

6. 6. Zitt E, König M, Vychytil A, et al: Use of sodium thiosulphate in a multi-interventional setting for the treatment of calciphylaxis in dialysis patients. Nephrol Dial Transplant 28(5):1232–1240, 2013. https://doi.org/10.1093/ndt/gfs548

7. 7. Nigwekar SU, Brunelli SM, Meade D, et al: Sodium thiosulfate therapy for calcific uremic arteriolopathy. Clin J Am Soc Nephrol 8(7):p 1162-1170, 2013. doi:10.2215/CJN.09880912

8. 8. Nigwekar SU: Phase 2 trial of phytonadione in calciphylaxis. American Society of Nephrology. Abstract TH-PO1188. Accessed May 16, 2024.