Renal - CKD Flashcards
what is CKD and how is it measured?
CKD = irreversible loss of renal function and/or structure over at least 3 mths, as a result of renal injury causing replacement of renal tissue by extracellular matrix - shrinking of functional cortex region.
Measured as decreased GFR (<60 ml/min/1.73m2) and presence of albuminuria (indicates kidney damage)
name the common causes of CKD
- T2DM (42%)
- HTN (28%)
- Glomerular disease, e.g. glomerulonephritis (7%)
- T1DM (4%)
- Cystic/hereditary kidney disease (4%)
- Infection - pyelonephritis
what are the risk factors for CKD?
- increasing age
- DM
- HTN and CVD
- smoking
- chronic use of NSAIDs
- African, Afro-Caribbean or Asian family origin
how is CKD classified?
According to GFR:
- stage 1: normal/high GFR, >90
- stage 2: mild decrease, 60-89
- stage 3a: mild-moderate decrease, 45-59
- stage 3b: moderate-severe decrease, 30-44
- stage 4: severe decrease, 15-29
- stage 5: ESRD (death likely without RRT), <15
According to albuminuria:
- 1: normal-mild increase, <3 mg/mmol
- 2: moderate increase, 3-30 mg/mmol
- 3: severe increase, >30 mg/mmol
describe the symptoms associated with CKD
Specific symptoms usually only develop in severe CKD:
- anorexia, nausea and vomiting
- fatigue and lethargy
- weakness and muscle cramps
- pruritis
- nocturia and polyuria
- insomnia and headache
- sexual dysfunction
- SOB (pulmonary oedema)
- peripheral oedema
which investigations would you request for a pt with suspected CKD?
Bloods:
- eGFR: assess renal function (repeat after 2 wks if abnormal to assess rate of change)
- creatinine: usually increased (can remain in normal range despite loss of >50% renal function)
- UandE: normal or decreased Na+, increased K+ and urea
- FBC, MCV, Hb: normocytic anaemia
- HCO3-: decreased
- calcium studies: progressive increase in PTH with decreased renal function
- ALP: raised when bone disease develops
Bedside tests:
- urinalysis: dipstick proteinuria suggests glomerular or tubulointerstitial disease; RBCs and red cell casts suggest proliferative glomerulonephritis; pyuria and white cell casts suggest interstitial nephritis or UTI
- spot urine collection for total protein:creatinine ratio: degree of proteinuria correlates with rate of CKD progression
- ECG and echo: to detect LVH and ischaemia, and to assess cardiac function
Imaging:
- renal USS: small echogenic kidneys seen in advanced CKD, structural abnormalities may be seen, e.g. polycystic kidneys
describe the medical management of a pt with CKD
- CVD prevention
- atorvastatin 20mg PO OD
- antiplatelets, e.g. warfarin or apixaban
- folic acid and vitB supplement (if at risk of nutritional deficiency) - BP control (aim for <140/90 mmHg)
- ACEi/ARB
- dialysis pts should be on restricted Na+ diet - mineral and bone disorders
- bisphosphonates if indicated for prevention and Tx of osteoporosis in pts with GFR >30
- cholecalciferol or ergocalciferol for pts with vitD deficiency
name the 3 types of RRT
- haemodylaysis
- peritoneal dialysis
- renal transplant
explain the possible haematological complications of CKD. How would you treat?
Normochromic, normocytic anaemia: mainly develops from decreased renal synthesis of EPO, but also involves iron deficiency (poor intake, occult bleeding), presence of uraemia inhibitors causing BM suppression (e.g. hepcidin, PTH, inflammatory cytokines), medications (e.g. ACEi).
Tx: replace iron (oral or IV) if low; EPO replacement if Hb still low
what is the effect of CKD on BP?
HTN: low GFR causes increased renin release and RAAS activation, resulting in Na+ and water retention.
what is the effect of CKD on bone health? how would you treat?
Renal osteodystrophy, e.g. osteomalacia, osteoporosis, soft tissue calcification…
- Decreased 1a-hydroxylation of vitD causes decreased Ca2+ absorption from gut and thus hypocalcaemia… increased PTH release and bone resprtion… hypercalcaemia.
- Renal phosphate retention… hyperphosphataemia.
Tx: decreased dietary phosphate intake; phosphate binders, e.g. calcium carbonate/acetate; calcium and/or active vitD (e.g. calcitriol) supplementation
What is the effect of CKD on electrolyte and waste balance?
- hyperkalaemia: loss of renal K+ excretion once GFR <20. Requires dialysis if K+ >7 mmol/L.
- azotaemia: decreased GFR causes decreases filtering of urea into urine, resulting in uraemia. Causes: general symptoms (nausea, anorexia), pruritis, pericarditis, haemorrhage (uraemia-induced platelet dysfunction), uraemic encephalopathy (asterixis, coma and death)
