Chronic Renal Failure Niroj Obeyesekere 3rd year student notes
What’s covered • The stages of CRF • Common causes of CRF • Modifiable and non modifiable RF for CRF • Approach to CRF diagnosis and management • Complications of CRF esp Renal bone disease and Anemia • Treatment of CRF complications • Basic understanding of dialysis hemodialysis and peritoneal dialysis
Factors that affect progression Non modifiable- Age Sex – males higher incidence Race – In US African Americans higher incidence. In UK Indian subcontinent higher incidence. Aborigines in Australia Genetics – HT, DM PCKD, ACE polymorphism - In Homo sapiens, the gene encoding ACE is located on the longarm of chromosome 17 Polymorphism involving the presence(insertion, I) or absence (deletion, D) of a 287-bp sequenceof DNA in intron 16 of the gene DD, ID, II. DD have high ACE activity
Factors that affect progression Modifiable Proteinuria Hypertension Metabolic factors Glycemia – initiation vs. progression Lipids – not in dialysis pts Smoking Alcohol and caffeine and HT not so robust
Management RRT includes Transplantation
Complications of Chronic Renal Failure • 1. Cardiovascular disease • 2. Anaemia • 3. Renal bone disease • 4. Metabolic acidosis • 5. Malnutrition • 6. Salt and water • 7. Hyperkalemia • 8. Bleeding diathesis
Complications of CRF • 9. Skin – pruritis, dry xerotic skin • 10. CNS –uremic encephalopathy, restless legs, peripheral neuropathy, • 11. Endocrine – Hyperparathyroidism, GH reduced, Testosterone levels low, prolactin levels high infertility in women • 12. Immunity - low
Renal Bone disease • 1. osteitis fibrosa – increased PTH, increased osteoclast and osteoblast activity and peritrabecular fibrosis- rugger jersey spine • 2. osteomalacia – defective mineralisation • 3. adynamic bone disease – low bone turnover • 4. osteopenia or osteoporosis • 5. combination
Pathogenesis – in osteitis fibrosa • Ca – bones (mineral), intracellular (protein bound) and extracellular (1/2 protein bound ½ free). • Vit D – reduced production in kidneys (1,25 from 25 by 1 -alpha hydroxylase) leads to decreased ca absorption from intestine. • PO4 retention occurs when GFR <20, prior to this increased PTH increases PO4 excretion in urine. • PTH – subperiosteal erosions
Pathogenesis • Osteomalacia – Aluminium toxicity – reduced osteoblast function • Adynamic bone disease – use of vit d, high calcium dialysate.
Clinical manifestation • Usually just biochemical abnormalities • Bone pain • Pruritis • Metastatic calcification and calciphylaxis.
Treatment • Calcium replacement • Phosphate binders – caltrate, alutabs, mylanta, renagel, lanthunum. • ViT D replacement D3 and D2 –but increases Po4 absorption and Ca absorption PTH between 3 to 5 times of normal
Anaemia • Normally normocytic normochromic • Reduced EPO • The EPO gene chromosome 7. Synthesised in fibroblast like interstitial cells in kidney and lesser degree liver.
Treatment • 1. Replace iron – iron sulfate, iron gluconate, iron fumurate • 2. IV iron – iron polymatose, sodium ferric saccharate (sucrose). • 3. EPO – aim for Hb 10 – 12.
CVD • Increased strokes • Pericarditis – rare now. • IHD • Arrhythmias • LVH • HT
Physiology of haemodialysis • HD describes the process whereby the solute composition of blood is altered by its contact with another solution through a semi-permeable membrane • HD removes solutes by: 1). Diffusion (mvt of solute across the membrane down a concentration gradient) 2). Convection (‘ultrafiltration’ solutes pushed through the membrane by a pressure gradient). Conventional HD relies mostly on diffusion.
Access for dialysis • Vascath – temporary (max 5 days) for acute dialysis (femoral, subclavian or internal jugular vein) • Permacath – tunnelled catheter (subclavian or internal jugular) • Arteriovenous fistula • AV Graft
Peritoneal Dialysis • PD uses the peritoneal membrane as a natural dialysis filter • PD solution is instilled into the peritoneal cavity and acts as the ‘dialysate’ • PD has some medical and lifestyle advantages over HD • Longterm technique survival after 5 years is low
Peritoneal Dialysis • Continuous ambulatory PD (CAPD) – patients do 3 to 4 exchanges during the day and one dwell overnight • Automated PD (APD) – a machine cycles dialysate in overnight and patients may have a dwell in during the day. • Main complications: PD peritonitis, membrane failure