Renal failure

Question 1

What’s the normal function of the kidneys?

Answer 1

Excretion of salt, water and waste products of metabolism (via urine)
Regulation of acid-base (H+) Regulation of blood pressure (renin)
Production of erythropoietin, activation of vitamin D (1α OHase)
Excrete (water soluble) drugs/metabolites

Question 2

How must plasma creatinine be interpreted?

Answer 2

Plasma creatinine must be interpreted in the context of the individual patient (ideally with previous measurements)
eg 200 micromol/l represents much more severe renal impairment in elderly, females, small, low muscle mass patients than in younger, muscular individuals

Question 3

What is acute renal failure/acute kidney injury?

Answer 3

Rapid loss of renal excretory function (over hours or days rather than weeks).
• Implies reversibility if underlying condition can be successfully treated.
There are three stages: pre-renal, renal, post-renal.

Pre-renal:
• Salt and water depletion (diarrhoea, vomiting, diuretics, fever, poor fluid intake)
• Haemorrhage (esp. gastrointestinal)
• Hypotension (heart failure, drugs, sepsis, shock)
• Renovascular disease

Renal: • Tubular necrosis (85%) more than half are originally due to pre-renal factors, remainder due to tubular toxins
• Interstitialnephritis(10%)
• Acute glomerulonephritis (5%)

Post-renal:
• Obstructiontooutflowfrombothkidneysorto outflow from a single functioning kidney
• Esp. prostate in males, Ca. cervix in females
• Rememberretroperitonealfibrosis,neurogenic bladder
• Intra-renal obstruction eg. Crystals or casts (esp. myeloma)
• Prognosisdependsonthatofunderlying condition, and on duration of obstruction

Question 4

What is chronic renal failure/chronic kidney disease?

Answer 4

Slowly progressive loss of excretory renal function. Original cause often unknown, usually irreversible
• Management aimed at slowing progression (esp. blood pressure control) and at consequences

Question 5

What are the consequences of renal failure?

Answer 5

Accumulation of: K+, urea, creat., H+, water, PO43-
Deficiency of: Erythropoietin- anaemia
Deficiency of: 1a vitamin D3 - hypocalcaemia - hyper-PTH
• Delayed drug excretion

Question 6

What happens in renal replacement therapy?

Answer 6

• Erythropoietin
• Vitamin D (one-alpha) • (Sodium bicarbonate)
• Dialysis & transplantation

Question 7

What anticoagulants are used?

Answer 7

• Heparin for dialysis: allow delay
• Warfarin for access patency
• Aspirin

Question 8

What are the general consequences of immunosuppression?

Answer 8

• Infection (correlation with corticosteroid dosage)
• Viral transmission with transplant (esp. CMV)
• Malignancy (esp. viral eg lymphoma, skin, cervix) [importance of UV exposure and skin type]
• Hypertension, dyslipidaemia, osteopaenia

Question 9

What are the adverse affects of cyclosporin?

Answer 9

• Nephrotoxicity
• Tremor
• Hirsutism
• Gingival hypertrophy (additive effect with nifedipine)
• Interactions (esp. macrolides, diltiazem)

Question 10

Dental care after renal transplantation?

Answer 10

• Good oral hygiene essential
• Gingival hypertrophy (cyclosporin, nifedipine)
• Increased susceptibility to infection • Antibiotic prophylaxis • Drug interactions esp. erythromycin etc.