Kidney Clinical Nutrition Lec12 PDF

Nutritional care during kidney and urinary tract Diseases  The Structure of the renal system The renal system consists of: 1) 2 kidneys. 2) 2 ureters. 3) urinary bladder.  The Kidney The kidneys are vital organs responsib...

Nutritional care during kidney and urinary tract Diseases  The Structure of the renal system The renal system consists of: 1) 2 kidneys. 2) 2 ureters. 3) urinary bladder.  The Kidney The kidneys are vital organs responsible for maintaining homeostasis. They perform excretion, regulation, and production of essential substances critical for the body's internal balance.  Excretory Functions Removal of metabolic waste products (e.g., urea, creatinine, uric acid). Excretion of foreign substances (e.g., drugs, toxins). Mechanism: Filtration at the glomeruli, tubular reabsorption, and secretion.  Fluid and Electrolyte Balance Regulates water balance through ADH and urine concentration. Controls electrolytes: Sodium (blood pressure, fluid balance). Potassium (muscle and nerve function). Calcium and phosphate (bone health). Maintains acid-base balance (pH 7.35–7.45).  Blood Pressure Regulation Via Renin-Angiotensin-Aldosterone System (RAAS): Renin secretion activates angiotensin and aldosterone. Increases sodium and water reabsorption. Direct regulation of blood volume through filtration and reabsorption.  Endocrine Functions Erythropoiesis: Produces erythropoietin (EPO) to stimulate red blood cell production. Activates vitamin D to calcitriol for calcium and phosphate absorption. Produces prostaglandins to regulate renal blood flow.  Osmolarity and Glucose Regulation Maintains osmolarity through the Loop of Henle's countercurrent mechanism. Prevents glucose loss by tubular reabsorption (threshold: ~180 mg/dL). Performs gluconeogenesis during fasting.  Summary of Kidney Functions Function Details Key Mechanism Excretion Removes wastes (urea, Filtration and secretion drugs) Fluid Balance Maintains hydration levels ADH regulates water reabsorption Electrolyte Balance Regulates Na+, K+, Ca2+, Hormonal regulation PO4 (aldosterone, PTH) Acid-Base Balance Maintains blood pH (7.35– Bicarbonate reabsorption, 7.45) H+ excretion Blood Pressure Regulates volume and Renin secretion, Na+ RAAS reabsorption Endocrine Produces EPO and EPO stimulates RBCs, activates vitamin D calcitriol aids Ca2+ absorption  Anatomy of the Kidney and nephron Collecting duct Formation of Urine  Classification of Kidney Diseases 1. Acute Kidney Diseases 1.1 Acute Kidney Injury (AKI) Definition: A sudden, reversible reduction in kidney function over hours to days, impairing fluid, electrolyte, and metabolic balance. Mechanism: 1.Pre-renal AKI: 1. Reduced renal perfusion from hypovolemia, hypotension, bleeding or cardiac dysfunction. 2. Mechanism: Low perfusion reduces GFR, leading to decreased filtration and toxin clearance. 2.Intrinsic AKI: 1. Direct injury to the renal parenchyma (e.g., ischemia, nephrotoxins). 2. Mechanism: Damage to tubular cells or glomeruli reduces reabsorption, filtration, and concentration capabilities. 3.Post-renal AKI: 1. Obstruction of urine flow (e.g., stones, tumors). 2. Mechanism: Backpressure damages nephrons and impairs filtration. Symptoms: Oliguria less than 500 ml/day (The normal range for 24-hour urine volume is 800 to 2,000 milliliters per day (with a normal fluid intake of about 2 liters per day). Edema and weight gain. Hyperkalemia (muscle weakness, arrhythmias). Uremia (nausea, confusion), and Proteinuria  2.Chronic Kidney Disease (CKD): Definition and complications Progressive and irreversible destruction of renal tissues and hence, decline in renal function over months to years, resulting in the buildup of uremic toxins, electrolyte imbalances, and metabolic disorders. Gradual irreversible deterioration of renal functions (over years). Characterized by a slow, steady decline in renal functions. Stages: Based on GFR (e.g., Stage 1: ≥90 mL/min, Stage 5: 3.5 g/day), hypoalbuminemia, edema, and hyperlipidemia Mechanism: Damage to the glomerular filtration barrier leads to protein loss. Compensatory hepatic lipoprotein synthesis increases cholesterol levels.(The liver tries to compensate for the loss of albumin and other plasma proteins by increasing protein synthesis, which isn’t selective, it also increases the production of lipoproteins, particularly LDL and VLDL, which raises the levels of cholesterol and triglycerides in the blood. This results in hyperlipidemia, a key feature of nephrotic syndrome) Symptoms: Generalized edema, Foamy urine, Weight gain hypertension, hyperlipidemia and ascites 3.2 Nephritic Syndrome Definition: Inflammation of the glomeruli, characterized by hematuria, hypertension, and mild proteinuria and impaired renal function. Also called: acute glomerulonephritides. ( a group of disorders characterized by intraglomerular inflammation, manifested clinically by hypertension, hematuria and edema) Mechanism: Immune-mediated usually post infection damage to glomerular capillaries causes leakage of blood and protein. Sudden in onset; short time; and proceed to either complete recovery, or development of chronic nephrotic syndrome, or ESRD Symptoms: Cola-colored urine (hematuria), Hypertension, Oliguria, mild edema. 4. Kidney Stones (Nephrolithiasis) Definition: Formation of mineral and salt crystals in the urinary system. Mechanism: 1.Supersaturation of urine with stone-forming substances (calcium oxalate, calcium phosphate, uric acid, cystine and struvite stones). Reduced inhibitors (e.g., citrate) that prevent crystallization. Symptoms: Severe flank pain. Hematuria. Nausea, vomiting. 5. End-Stage Renal Disease (ESRD) Definition: Total and irreversible damage of renal tissues leading to kidney failure requiring dialysis or transplantation. (Stage 5 Chronic liver failure, GFR < 15ml/min Mechanism: Progressive nephron loss leads to toxin accumulation, electrolyte imbalances, and metabolic acidosis. Symptoms: Uremia (confusion, pruritus). Severe fatigue. Muscle cramps, fluid overload.  Clinical Nutrition for Kidney Diseases General Principles 1.Protein: Balance to prevent malnutrition and uremic toxin buildup. 2.Energy: Provide adequate calories to prevent catabolism. 3.Electrolytes: Maintain sodium, potassium, calcium and phosphorus within safe levels. 4.Micronutrients: Address deficiencies from diet restrictions or losses. 5.Fluids: Match intake to output to prevent overload. 1. Acute Kidney Injury (AKI) Clinical Nutrition by Disease ❑ Medical nutrition therapy (MNT) depends on: ▪ Patient’s nutritional status and catabolic rate ▪ The phase of ARF ▪ The amount of urine output ▪ Clinical indications such as: uremia, or continuous renal replacement therapy (CRRT). ❑ MNT for patient with ARF must be individualized. The goals of nutritional management for patients with (ARF) are to: ▪ Minimize uremia and maintain the chemical composition of the body as close to normal as possible ▪ Preserve body protein stores until restoring normal renal function ▪ Maintain fluid, electrolyte, and acid-base homeostasis; and prevent nutritional deficiencies. ▪ Patients who have adequate (GI) function but can not tolerate food because of mental status, anorexia, nausea, or poor compliance should receive nourishment by enteral tube feeding. ▪ Total parenteral nutrition (TPN) for dysfunctional of (GI) tract. ▪ Peripheral insulin resistance may cause hyperglycemia in catabolic patients with ARF, and their blood glucose levels therefore should be closely monitored.  Clinical Nutrition by Disease 1. Acute Kidney Injury (AKI) (cont.) 1.Protein: 1. Mechanism: Prevents muscle wasting and supports repair. 2. Recommendation: A. Non-dialysis/non catabolic: 0.8–1.0 g/kg/day. B. Hemodialysis: 1.2–1.5 g/kg/day C. Severe catabolic patients and under CRRT: up to 2.5 g/kg/day Examples: Eggs, fish, tofu (It is made from dried soybeans (Vegetable protein. It contains all the essential amino acids your body needs and is rich in minerals and vitamins, including calcium, manganese, iron and vitamin A) 2.Energy: 1. Mechanism: Prevents catabolism. 2. Recommendation: 25–30 kcal/kg/day. 3. Examples: Brown rice, olive oil. 3.Electrolytes: 1. Sodium: