Week 10: Renal Biochemistry Flashcards
Explain the main functions of the kidneys. (7)
- Regulates water and electrolyte in the body.
- Glucose + protein retention.
- Maintains acid/base balance.
- Regulates BP via RAAS system.
- Excretes waste products, toxic substances and medicines.
- Endocrine functions (Vit. D activation)
- Needs cardiac output for perfusion.
What is the ref. range for Urea?
3.0-6.5mmol/L
Where is urea produced? (1)
Protein/Amino acid breakdown via liver.
What process does urea undergo for elimination? (1)
Glomerular Filtration
Where in the body is urea reabsorbed? (1)
Kidney Tubules
What can cause high urea levels? (3)
- Dehydration
- Concurrent Infection
- Gastric blood loss
What can cause low urea levels? (5)
Oedema
Low Protein Diet
Pregnancy
Chronic nutrition status
Low liver function
What is the reference range for creatinine? (1)
50-120umol/L
Where is creatinine produced? (1)
Muscle
What is the main function of creatinine? (1)
Maintains muscle mass.
What is creatinine? (1)
Waste product of muscle catabolism (breakdown)
How is creatinine cleared from the body? (1)
Glomerular Filtration
Explain how creatinine is used. (1)
Determines kidney function.
What is the Cockroft-Gault equation? (1)
(140 - Age) x weight (kg) x Constant / serum creatinine (umol/L)
Female = 1.04
Male = 1.23
What is AKI? (1)
A rapid deterioration of kidney function over hrs or days.
Explain why creatinine is used rather than eGFR in patients with AKI. (1)
e stands for estimated in eGFR. Hence, it’s more accurate to use creatinine.
What is the SCr criteria for stage 1 AKI. (2)
Increase >26umol/L within 48 hrs
OR
Increase ≥ 1.5-1.9 x ref. SCr
What is the urine output criteria for stage 1 AKI? (1)
<0.5ml/kg/hr for > 6 consecutive hrs.
What is the SCr criteria for stage 2 AKI. (1)
Increase ≥ 2-2.9 x ref. SCr.
What is the urine output criteria for stage 2 AKI? (1)
<0.5ml/kg/hr for > 12 hrs.
What is the SCr criteria for stage 3 AKI? (3)
Increase ≥ 3 x ref. SCr OR
Increase ≥ 354umol/L OR
Commenced on renal replacement therapy (RRT) irrespective of stage.
What is the urine output criteria for stage 3 AKI? (2)
<3ml/kg/hr for > 24 hrs
OR
Anuria for 12 hrs
What information do you need for interpreting SCr levels?
Baseline.
What are the consequences of AKI? (4)
Increased risk of morbidity/mortality.
Small rise in SCr = poor px outcomes.
Increase hospital stay/no. of admissions.
Px needing long-term renal replacement therapy.
What are the pre-renal causes of AKI? (3)
Reduced perfusion: Hypovolaemia - dehydration/burns, Cardiac/vascular disease, reduced CO/low BP.
Sepsis/ Infection
Haemorrhage
What are the intrinsic causes of AKI? (4)
Kidney disease
Vasculitis
Necrosis
Rhabdomyolysis
What are the post-renal causes of AKI? (3)
Fluid retention
Obstruction (renal stones)
Prostate cancer.
What are the risk factors for AKI? (12)
Elderly
Sepsis, Hypovolaemia + Hypotension
Diabetes
HF
Liver Disease
Atherosclerotic PVD
CKD
Hx of AKI (monitor renal function)
Surgical procedure
Medications (avoid nephrotoxic)
Use of contrast media
Low Albumin
Give e.g. of medicines you need to avoid in px with AKI. (4)
Contrast Media
Diuretics
ACEi/ARBs
Metformin/SGLT2i (not nephrotoxic but dangerous in low CrCl)
NSAIDs
What type of monitoring do you need to consider in AKI? (2)
Renal function
Electrolytes (U&E)
What are the sick day rules in AKI?
Withold contrast media and DAMN drugs.
What is CKD?
Reduction in kidney function or structural damage (or both) present for > 3 months.
Explain the CKI GFR classification. (3)
G1 = Normal/High = ≥ 90ml/min/1.73m
G2 = 60-89ml/min/1.73m
G3a/b = 30-60ml/min/1.73
Explain the CKI’s albumin classification. (3)
A1 = <30mg/g or <3mg/mmol
A2 = 30-300mg/g or 3-30mg/mmol
A3 = >300mg/g or >30mg/mmol
What are the risk factors for CKD? (10)
Diabetes (cause of G5)
Hypertension
Proteinuria / Albuminuria
Obesity
Smoking
Hyperlipidaemia
Age
CVD
NSAIDs use
AKI
What are the signs and symptoms of kidney disease? (10)
Puffy eyelids
High BP
Loin Pain
Blood/tea colour/frothy/cloudy urine
Discomfort/pain when passing urine.
Difficulty in passing urine
Passing urine frequently
Nocturia
Passing stone / sand with urine
Swollen ankles
What are the signs and symptoms of kidney failure? (8)
Poor appetite
N+V
Tiredness
Anaemia (Paleness)
SOB
Drowsiness
Coma
Convulsion
Provide examples of preventative measures against kidney disease. (8)
Maintain adequate fluid intake (2L a day)
Good personal hygiene (prevents UTI)
Avoid excessive meat and salt intake.
Px with kidney stones, avoid high calcium intake.
Good control of diabetes + BP.
Px with kidney stones/UTO, seek early and adequate tx.
Early detection of kidney disease by routine urine examination and blood test for kidney function.
Early tx of kidney disease.
Explain the management process of CKD with persistent proteinuria without diabetes. (2)
If ACR = ≥70ng/mmol, refer for nephrology assessment and offer ACEi/ARB (titrated to highest licensed dose that they can tolerate).
If ACR = 30-70mg/mmol, consider discussing with nephrologist if eGFR declines/ACR increases. Give Dapagliflozin/Empagliflozin.
Explain the interventions introduced in patients with cardiovascular risk. (4)
Primary/Secondary prevention (Statins/hypertension)
Diabetes control
Exercise
Smoking
What are the complications of CKD? (3)
Renal Anaemia = Folate/B12/Fe/Epoetin stimulating agents.
CKD Mineral and bone disorder = reduce phosphate: diet, phosphate binders, cinacalcet, vit. D.
Metabolic acidosis = sodium bicarbonate.
What do you need to consider regarding medications and adjustments? (3)
Refer to renal drug handbook.
Dose changes occur at <30ml/min
Effect on medication = accumulation in reduced eGFR (normally when >25% of drug renally excreted), altered drug distribution (protein binding) and decrease in drug metabolism - digoxin, insulin, vitamin D.
Explain the management process of CKD patients with hypertension. (5)
ACEi/ARBs
Slow progression proteinuria + CKD
Risks = hypotension + falls, hypoperfusion of kidneys - AKI = stop in AKI but good for CKD
Monitoring = initial drop but slow prgression.
Explain the management process of CKD patients with diabetes. (4)
SGLT2i beneficial in CKD = risk of DKA.
Metformin = risk of lactic acidosis (reduce dose 1g <45ml/min, stop <30ml/min)
DPP4i (low eGFR) - no minimum for linagliptin.
Insulin.
Explain the use of NSAIDs in renally impaired px. (3)
Caution in CKD = only use if absolutely necessary @ lowest dose and monitoring.
Increase risk of AKI
Fluid retention.
Explain the management process of CKD patients presenting with pain. (3)
Step 1: Mild pain (Paracetamol 1-2 tabs QDS)
Step 2: Moderate pain (Regular paracetamol + weak opioid +/-adjuvant)
Acute Pain: Codeine/Tramadol with caution or low dose oxycodone 2.5-5mg
Step 3: Severe Pain
Regular paracetamol + strong opioid +/- adjuvant
Acute pain: oxycodone IR titrate to effect.
Chronic pain: Oxycodone M/R or Fentanyl patch (unlikely to accumulate vs. morphine)
Explain which medications would you need to consider monitor in patients with AKI .
Metformin = increased risk of lactic acidosis. (Stop temporarily, if renal returns to baseline, reintroduce)
ACEi/ARB/Diuretics = stop temporarily and review renal function (detrimental to recovery of kidney function)
Statins - withold temporarily due to increased risk of myopathy.
Aspirin - continue
DOACs - withold consider LMWH.
SGLT2i - withold due to risk of DKA.
Explain which medications would you need to consider monitor in patients with CKD.
Metformin - Avoid if SCr >150umol/L or eGFR <30ml/min, caution if SCr is between 130-150umol/L or eGFR <45ml/min (lactic acidosis risk)
ACEi/ARB/Diuretics = Renal function stable so no reason to alter current dose, monitor renal function.
Simvastatin - tolerating dose, renal drug handbook suggests dose used in practice.
Aspirin - continue
DOACs - dose adjust acc. to renal function via handbook.
