DPD: Renal disease Flashcards
What are 5 main functions of the kidney?
Filtration + excretion of waste products
Electrolyte homeostasis
Hormone production (EPO+ 1.25 Calcitriol)
BP control via RAAS, prostaglandins + bradykinin
Acid base homeostasis
What must be considered when interpreting eGFR?
Only relevant in stable patients
Not valid in AKI
Dependent on muscle mass
What variation in urine colour may be seen? What causes each of these?
Red: myoglobinuria or haemoglobinuria, food dyes, beetroot, porphyria, rifampicin
White: pyuria, phosphate crystals, chyluria
Black: haemoglobinuria , alkaptonuria
What is urine PCR?
Total urine protein excretion (albumin, light chains + other globulins) divided by urine creatinine
What is urine ACR?
Urine albumin concentration divided by urine creatinine.
What is AKI?
A rapid deterioration in renal function over days
with
Accumulation of nitrogenous waste products
Potentially life threatening metabolic consequences
+/- reduction in urine output
What figures define AKI?
Serum Cr rise >26 umol/L within 48 hrs
Or
Serum Cr rise 1.5x the reference value known or presumed to have occurred within 1 week
Or
Urine output < 0.5ml.kg/hr for 6 consecutive hours
List 10 risk factors for AKI?
Age >75 Pre existing CKD (eGFR <60) Previous ep of AKI Debility + dementia HF Liver disease DM Hypotension Sepsis Hypovolaemia Nephrotoxins e.g. gentamicin, NSAIDs Continued antihypertensives in setting of hypotension
How can the causes of AKI be classified? What is the prevalence of each cause?
Pre-renal ~20%
Intrinsic renal ~50%: problem in kidney
Post renal ~15%
What is the problem in pre-renal AKI? List 3 causes of this What do you need to examine
Hypovolaemia Low CO Hypotension Renal artery thrombosis is BP low? volume status, JVP, BP + postural drop?
List 8 causes of renal AKI
Acute tubular necrosis Glomerulonephritis Myeloma Vasculitis Nephrotoxins, contrast, rhabdomyolysis Interstitial nephritis HUS/ TTP Malignant HTN
What is the problem in post-renal AKI? List 3 causes of this. What investigation should you perform?
Ureteric obstruction Urethral obstruction Blocked urinary catheter Bladder tumour US scan
What is CKD?
impaired kidney function, usually progressive, potentially resulting in ESKD over months to years, often multifactorial.
Not reversible.
What signs and symptoms are caused by AKI?
Symptoms of uraemia (nausea, vomiting, anorexia)
Decreased urine output
Features of the underlying disease
Systemic features (rash, myalgia, arthralgia, headaches)
What biochemistry may be found in AKI?
High serum urea + creatinine
Acidosis
Hyperkalaemia
Salt + water retention
What is found in the urine in the 3 classes of AKI?
Glomerular disease: red cells, red cell casts, proteinuria (often heavy)
Tubular disease: Minimal blood, small protein, granular or white cell casts
Post-renal: no blood or protein, no casts
What 9 investigations are necessary in AKI?
Volume status (for ATN) Urine microscopy + dipstick US scan to detect obstruction ANCA, Anti-GBM, SLE immunology (ANA, dsDNA, complements) Creatinine kinase FBC, clotting Inflammatory markers Myeloma screen (protein electrophoresis, urine BJP) May need biopsy
What immediate complications of AKI need urgent treatment?
Potassium (kills) Pulmonary oedema (kills) Acidosis HTN Uraemia (brain, nerves, heart)
How is hyperkalaemia treated?
IV Ca Insulin + dextrose Nebulised salbutamol Calcium resonium or newer binding agent Dialysis
What is the aetiology of CKD? Often CKD patients present at what stage? What size are their kidneys?
A “syndrome” for which there is a cause, although often not identified
End stage
Often small kidneys
What is the epidemiology of CKD?
Common
>40% of >75s
List 7 risk factors for CKD
Elderly HTN Diabetes IHD FH CKD African American Obesity
List 6 causes of CKD
Diabetes (~30%)
Chronic glomerulonephritis (~30%)
Vascular diseases inc. HTN, IHD (~15%)
Autosomal dominant polycystic kidney disease (~10%)
Congenital/reflux/childhood infections
Genetic risks .. with another insult (eg ApoL1 risk variants in black patients)
What is the key to preventing progression of CKD? How is this achieved?
BP control (v low) + reducing proteinuria
ACEi/ARBs
Increasingly SGLTi drugs
Minimising other CV risks eg smoking
List 2 complications of CKD
Calcification of abdominal aorta
Predisposes to cardiovascular disease
What is nephrotic syndrome?
Proteinuria >3g/24h or PCR >300mg/mmol
Hypoalbuminuria
Oedema
What primary renal aetiologies can cause nephrotic syndrome?
Minimal change disease (glomerular)
Membranous nephropathy
What secondary renal aetiologies can cause nephrotic syndrome?
DM
SLE
Myeloma
Amyloid
What investigations are necessary in nephrotic syndrome?
Quantitate proteinuria (urine PCR) Serum albumin + cholesterol Serum creatinine, U+Es Glucose SLE tests Virology (Hep B,C + HIV) Myeloma screen Renal US Renal biopsy
How is nephrotic syndrome managed?
Control oedema: low salt diet, diuretics
ACEi/ARB (reduce proteinuria)
Treat the cause
Sometimes steroids or immunosuppression
What is uncontrolled proteinuria is a major risk for?
Progressive CKD
Ultimate ESKD
Where is the pathology in haematuria? What may cause this?
Glomerulus
Thin glomerular basement membrane disease or variant e.g. Alport’s syndrome
IgA nephropathy
What investigations are used for haematuria if cancer/ kidney stones are most likely the cause?
Imaging (US, CT)
Cystoscopy
What investigations are used for haematuria if glomerular injury is most likely the cause?
Check urine for protein
eGFR
Blood tests for underlying systemic or immune disease
Renal biopsy.
What is the prognosis for ESKD?
No recovery possible
Need dialysis or a transplant or not do either + treat symptoms (conservative care)
