Renal Flashcards
What is AKI and what are the criteria for diagnosis?
Acute drop in kidney function.
- Creatinine rise >25micromol/l in 48 hours
- Creatinine rise >50% in 7 days
- UO <0.5ml/kg/hr for >6 hours
Give 5 risk factors for AKI.
Chronic kidney disease Surgery/infection Heart failure Diabetes Liver disease Older age (above 65 years) Cognitive impairment Nephrotoxic medications such as NSAIDS and ACE inhibitors Use of a contrast medium such as during CT scans
What are the pre-renal causes of AKI?
Most common. Inadequate perfusion due to:
Dehydration
Hypotension (shock)
Heart failure
What are the renal causes of AKI?
Intrinsic kidney disease leading to reduced blood filtration due to:
Glomerulonephritis
Interstitial nephritis
Acute tubular necrosis
What are the post-renal causes of AKI?
Obstruction to outflow of urine from the kidney due to:
Kidney stones
Masses such as cancer in the abdomen or pelvis
Ureter or uretral strictures
Enlarged prostate or prostate cancer
What would you see on urinalysis in infection?
Leucocytes and nitrites
What would you see on urinalysis in acute nephritis?
Protein and blood
What would you see on urinalysis in diabetes?
Glucose
What are the indications for ultrasound in AKI?
To look for obstruction. Not necessary if another cause found.
How is AKI managed?
Prevention - stop nephrotoxic medications eg NSAIDs fluid balance especially in pre-renal Relieve obstruction if post-renal cause unknown or complications risk - get specialist advice
Give 4 complications of AKI.
Hyperkalaemia
Fluid overload –> HF, pulmonary oedema
Metabolic acidosis
Uraemia (high urea) - encephalopathy, pericarditis
Give 5 causes of CKD.
Diabetes Hypertension Age-related decline Glomerulonephritis Polycystic kidney disease Medications such as NSAIDS, proton pump inhibitors and lithium
What is CKD?
Permanent and progressive decline in kidney function.
Give 5 risk factors for CKD.
Older age Hypertension Diabetes Smoking Use of medications that affect the kidneys
How does CKD present?
Usually asymptomatic and diagnosed on routine testing Itching loss of appetite Nausea Oedema Muscle cramps Peripheral neuropathy Pallor Hypertension
How is CKD diagnosed and staged?
You need eGFR <60 or proteinuria. Urine albumin creatinine ratio >3mg/mmol. This gives you an A score - (A1 = <3mg/mmol) A2 = 3-30mg/mmol A3 = >30mg/mmol eGFR 2 tests 3 months apart, gives you a 'G score' (G1 = >90 - not CKD) G2 = 60-89 G3a = 45-59 G3b = 30-44 G4 = 15-29 G5 = <15/ end stage
When is renal USS indicated in someone with reduced eGFR?
Accelerated CKD, haematuria, family history of polycystic kidneys, evidence of obstruction.
Give 5 complications of CKD.
Anaemia Renal bone disease Cardiovascular disease Peripheral neuropathy Dialysis related problems
What are the NICE indications to refer to a specialist in CKD?
eGFR <30 (G4/5)
ACR >70 mg/mmol (A3)
Accelerated progression - decrease in eGFR of 15, of 25%, or 15ml/min in 1 yr
htn despite 4 antihypertensives
How is CKD managed?
Can’t cure it but can:
slow progression by optimising control of diabetes and hypertension (ACEI) and treating glomerulonephirits;
reduce risk of complications with exercise, smoking cessation, specialised dietary advice and atorvastatin 20mg
and treat complications:
Sodium biarb for met acidosis
iron and epo for anaemia
vit D for bone disease
dialysis or transplant for end stage failure
How does CKD cause anaemia?
It is an anaemia of chronic disease.
Kidney usually produces EPO which stimulates RBC production. Kidney disease –> less EPO –> anaemia.
How is anaemia of CKD treated?
PO or IV iron
Erythropoietin.
Blood transfusions should be limited as they can cause allosensitisation, so transplanted organs are more likely to be rejected.
What is CKD-MBD?
Chronic kidney disease mineral and bone disorder, aka renal bone disease.
The kidney is also unable to convert vitamin D to its active form, which is needed to absorb calcium and regulate bone turnover. Reduced phosphate excretion by the kidneys leads to hyperphosphataemia, so the parathyroid glands excrete more PTH, leading to increased osteoclast activity, which cause calcium to leach from bones into blood.
The result is osteomalacia (softening), osteoporosis (reduced density) and osterosclerosis (hardening due to reaction from the osteoblasts)
What would you see on spine X ray in CKD-MBD?
Rugger jersey spine - osteomalacia in the centre of the vertebra, sclerosis at the ends, so looks stripy
How is renal bone disease managed?
Active vit D eg alfacalcidol, calcitriol
Low phosphate diet
Bisphosphonates for osteoporosis
Give 5 indications for acute dialysis in patients with a severe AKI.
Severe Acidosis that doesn’t respond to treatment
Electrolyte abnormalities eg severe, unresponsive hyperkalaemia
Intoxication (overdose of certain medications)
Severe and unresponsive pulmonary Oedema
Uraemia eg seizures, reduced consciousness
What are the indications for long term dialysis?
End stage renal failure (CKD stage 5 ie eGFR <15)
Acute indications continuing long term
What is peritoneal dialysis?
Uses the peritoneal membrane as a filtration membrane. Dialysis solution containing dextrose is added to the peritoneal cavity using a Tenckhoff catheter. Ultrafiltration occurs from the blood, across the peritoneal membrane, into the dialysis solution. The dialysis solution is then replaced, taking away the waste products.
It can be continuous ambulatory (change the fluid multiple times a day) or automated (overnight, a machine replaces the fluid overnight)
Give 5 complications of peritoneal dialysis.
Bacterial peritonitis - dextrose –> bacterial growth
Peritoneal sclerosis (thickening and scarring of the peritoneal membrane)
Ultrafiltration failure (patient absorbs the dextrose so the filtration gradient is reduced over time)
Weight gain due to absorbing the carbohydrate
Psychosocial effects
What is haemodialysis?
Blood is filtered by a haemodialysis machine. Requires good IV access using either a tunnelled cuffed catheter or AV fistula.
