Chronic kidney disease (URO) Flashcards
Define chronic kidney disease.
CKD is defined as abnormalities of kidney structure or function (GFR<60mL/minute/1.73m^2), present for >=3 months, with implications for health
What are abnormalities in kidney structure and function found in chronic kidney disease?
GFR<60mL/minute/1.73m^2 OR the presence of one or more of the following:
- albuminuria/proteinuria
- urine sediment abnormalities e.g. haematuria
- electrolyte abnormalities due to tubular disorders
- abnormalities detected by histology
- structural abnormalities detected by imaging
- Hx of kidney transplantation
What are some causes of chronic kidney disease? (5)
- diabetic nephropathy (diabetes)
- hypertensive nephropathy (hypertension)
- glomerulonephritis
- polycystic kidney disease
- heat stress nephropathy (environment/climate)
What are the most common causes of chronic kidney disease? (2)
Diabetes mellitus & hypertension
What is the most common genetic cause of chronic kidney disease?
Polycystic kidney disease
- autosomal dominant
- screen relatives with abdominal ultrasound
What are the mechanisms of damage in chronic kidney disease?
(Low-yield)
- renal injury –> increased intra-glomerular pressure + glomerular hypertrophy as compensation to maintain filtration
- glomerular permeability to TGF-beta, fatty acids, pro-inflammatory markers + protein –> mesangial matrix expansion, inflammation, fibrosis + scarring
- increase in angiotensin II –> upregulates TGF-beta –> collagen synthesis + scarring
- inflammation + reduced blood supply –> tubulo-atrophy + interstitial fibrosis
What are clinical features of CKD mainly manifestations of? (3)
- uraemia - lack of excretion of toxic substances
- anaemia - lack of EPO produced by kidney
- hyperphosphatemia - lack of excretion of toxic substances
How can CKD often present?
Often asymptomatic - may be finding of routine blood test or urine test
What are the clinical features of CKD?
- fatigue (uraemia/anaemia)
- oedema (peripheral/pulmonary - due to salt and water retention + hypoalbuminemia)
- nausea and vomiting (urea accumulation)
- pruritus (urea accumulation)
- restless legs (uraemia)
- anorexia (urea accumulation)
- foamy urine (proteinuria)
- cola-coloured urine (haematuria)
- dyspnoea, orthopnoea (pulmonary oedema due to reduced urine output)
- Kussmaul’s respiration (metabolic acidosis, deep inspiratory efforts without tachypnoea)
- seizures (advanced disease, increase in unexcreted toxins)
- infection-related glomerular disease (hepB&C, syphilis, streptococcal pharyngitis)
- arthralgia & rashes (concomitant autoimmune disorder)
- enlarged prostate gland (obstructive uropathy)
- symptoms of hypocalcaemia (due to 1-alpha-hydroxylase deficiency)
What are the symptoms of hypocalcaemia in CKD? (4)
- Convulsions (muscle twitching)
- Arrhythmias
- Tetany
- Paraesthesia
(CATs go NUMB)
What might you find on examination of a patient with CKD? (7)
- skin pigmentation
- uraemic frost
- purpura
- hypertension
- peripheral vascular disease
- cardiac arrhythmias: increased K+
- asterixis in encephalopathy
What are the risk factors for CKD?
- diabetes mellitus
- hypertension
- age>50
- childhood kidney disease
- smoking
- obesity
- black/Hispanic ethnicity
- Fx of CKD
- autoimmune disorders
- male sex
- long-term NSAID use
- high uric acid levels
What are the 1st-line investigations for CKD?
- renal chemistry (U&Es)
- estimation of GFR (equation using serum creatinine)
- serum cystatin C and cystatin C-based estimation of GFR (when serum creatinine inaccurate e.g. extremes of muscle mass)
- urinalysis
- urinary albumin (ACR)
- renal ultrasound
What do U&Es (renal chemistry/profile) show for CKD?
- elevated serum creatinine (may be falsely low in conditions of low muscle mass e.g. older, malnourished, liver failure)
- electrolyte abnormalities (tubular disorders –> metabolic acidosis) e.g. hyperkalaemia, hypocalcaemia
What can indicate if kidney injury is chronic and not acute?
Hypocalcaemia
(Kidney cannot produce 1-alpha-hydroxylase)
What is the GFR in CKD?
<60mL/minute/1.73m^2
When is GFR not a good measurement in CKD?
- reduced muscle mass –> overestimation of GFR
- increased muscle mass –> underestimation of GFR
What can urinalysis show for CKD?
Haematuria and/or proteinuria
What results does ACR (urinary albumin) show for CKD?
To check for proteinuria
Moderately increased ACR 30-300mg/g
What is the 1st-line imaging modality for kidney structure and what might you see (CKD)?
Renal ultrasound - small kidney size; presence of obstruction/hydronephrosis; kidney stones
(Large kidneys if diabetes uncontrolled in early diabetic kidney disease)
What might BNP be like in CKD?
Renal dysfunction (GFR<60) can cause a raised serum natriuretic peptides
What might FBC show in CKD?
Normocytic, normochromic anaemia due to EPO deficiency
When is kidney biopsy done for CKD?
For infectious causes, glomerular nephrotic and nephritic syndromes
What calcium/phosphate/PTH levels would we see in CKD?
- low calcium
- high phosphate
- high PTH
- low vitamin D