GI, kidney Flashcards
Functions of the kidney. How much filtrate it clears and urine it makes every day
-2 kidneys exchanges water and salts to produce urine which goes into renal pelvis, ureter, bladder, urethra, then outside world.
-180L of filtrate per day
-1.5L urine
Function and structure of a nephron
-functional unit of the kidney. Converts blood into urine
1-the glomerulus (filtration occurs)
2. Bowman’s capsule (collects filtrate)
3. Proximal tubule (reabsorption)
4. loop of henle (water and nutrient absorption into blood)
5. distal tubule
6. Collecting duct
How many nephrons in a kidney. Does it increase or decrease with age
~1 million
-decreases with age so more likely to have chronic kidney disease
What gland sits on top of the kidney. What hormones it produces
Adrenal gland.
cortisol, aldosterone, adrenaline, and noradrenaline
How is kidney function assessed
-creatine clearance
-Plasma creatine concentration
-estimated glomerular filtration rate
What is creatine. Normal plasma clearance value in females and male. What high and low values suggests
-Creatine is derived from metabolism in skeletal muscles and meat in diet
-95 +/- 20 mL/min in females
-120 +/- 25 mL/min in males
High= low GFR (as glomerulus hasn’t been able to clear filter it)
Low= low muscle mass
What is a healthy GFR. What value do you need dialysis
-125 ml/min = healthy
>100 is normal
<10 you need dialysis [stage 5 CKD]
What patients can estimated GMF not be used in
Only for people with average heights so Cannot be used in pregnant people, amputees, short people
Explain stage 1-5 of chronic kidney disease: the GFR and treatment
1: 90+. Normal function, but urine or structural abnormality.
2: 60-89. Mildly reduced kidney function.
3: 30-59: Moderately reduced renal function.
4: 15-29. Severely reduced Renal function
5. <15. >700 creatine. Endstage kidney failure
Stage 1-3= observe, control BP, address risk factors
Stage 4= Control BP, diet restriction, EPO and vit D supplements. Plan for end stage renal failure.
Stage 5= dialysis, transplant
Risk factors for chronic kidney disease
-diabetes
-old age
-polycystic kidneys
-heart disease, Peripheral vascular disease - renal artery stenosis
- ACEI or diuretics, family history of renal problems
Signs and symptoms of CKD (lots.)
-hypertension
-normocytic normochromic anaemia -tired, pale, unwell
-anorexic, nausea, vomitting, itch, confusion, agitated
-impaired clotting, increased bleeding
-pulmonary and peripheral oedema, cramps, tremor, twitches
-increased infection risk
-osteodystrophy
What blood components increase and decrease in CKD
-Increased BP, creatine, potassium (hyperkalaemia), prostacylin, urea (uraemia)
-low GFR
-reduced EPO (anaemic)
-Low RBC due to marrow fibrosis, renal loss, And increased fragility with consequent early destruction
-reduced vit D and Ca
-reduced vW factor and thromboxane
-impaired platelet adhesion
-metabolic acidosis
How CKD affects drug prescribing
-Reduced rate of elimination of renally excreted drugs = may accumulate e.g. opiates
-Reduced protein binding of acidic drugs (eg. phenytoin)
-increased binding of basic drugs (e.g. lignocaine)
-Nephrotoxic drugs may worsen renal function e.g gentamicin, NSAID’s
-immunosupression
Give examples of drugs to avoid and reduce in CKD
-Gentamycin (used in prophylaxis) is nephrotoxic = AVOID
-Erythromycin =REDUCE or AVOID if transplant and taking ciclosporin. Makes cyclosporin more toxic
-Dose reduction with acyclovir, amoxicillin, ampicillin, cefalexin, and erythromycin
-Tetracyclines other than doxycycline =AVOID
-NSAIDs =AVOID, except in mild kidney impairment
- BDZ excreted in kidney so IV sedation used in tertiary care
Is prophylaxis required for CKD before dental procedures
-Routine prophylaxis is not required for dental procedures, whether they are on dialysis, immunosuppressed transplant patients, have AV fistula
-consider if had infection after previous extraction
Immunosupressants for patients with kidney transplant. Oral side effects
-Prednisolone
-Azathioprine
-MMF
-Tacrolimus, sirolimus
-Cyclosporin A
-predisposition to infection - candiosis, herpes. Increased cancer risk (immune system reduced ability to identify abnormal cells). Cyclosporin can cause gingival overgrowth
Although rare, kidney disease is linked with orofacial digital syndrome. What are the signs and symptoms of this
-cleft palate
-bifid lobulated tongue
-hypo or hyperdontia
-limb and skeletal abnormalities
What does dialysis involve. Where is a fistula created
-remove waste products and excess fluid from the blood when the kidneys stop working properly. It often involves diverting blood to a machine to be cleaned
-patients anticoagulated using heparin (half life 6 hours) to prevent clotting
-arterio-venous fistula at the ACF or wrist (Risk of damage and haemorrhage as very turbulent blood flow)
When is the best time to dentally treat a patient receiving dialysis on heparin
-heparin at time of dialysis to prevent clotting in the circuit
-heparin has short half life.
-Day after dialysis = best time to treat these patients as heparin will have worn off but dialysis will have peaked so renal function optimal
What is nephrotic syndrome
-Proteinuria with hypoalbuminaemia= too much protein in urine
-Leads to oedema (no oncotic pressure, fluid leaks into tissues)
-Can be secondary to poorly controlled type 2 diabetes
Why osteodystrophy can be a feature in kidney disease
-Increased phosphate, decreased plasma Ca
-High PTH which draws calcium out of the bones
-There is a failure in conversion of 25-HCC into 1,25-HCC = leading to secondary hyperparathyroidism
-Also the decreased vit D in CKD causes low plasma Ca
What type of anaemia do CKD patients have
normocytic, normochromic anaemia
due to failure production of erythropoietin
Why CKD can impair haemostasis
-marrow fibrosis (FULL BLOOD COUNT AFFECTED = reduced platelet count and function so clotting issues)
-Impaired platelet adhesiveness
-Decreased von Willebrand’s factor
-Decreased thromboxane
-Increased Prostacyclin (vasodilation)
-Heparinisation – regular for dialysis
Oral and dental considerations for CKD
-Impaired haemsotasis
-Reduced excretion so affects drugs
-Incidence of oral ulceration/ infection increased
-Gingival hyperplasia with ciclosporin
-Beware of skin cancers and increased infection (due to immunosuppression)
-Dialysis patients may experience SIALOSIS
-Palatal and buccal keratosis sometimes seen
-CKD in children= delayed growth, delayed tooth eruption, enamel hypoplasia
-ADVISE PT NOT TO SWALLOW BLOOD POST-EXTRACTION –high protein in blood can exacerbate kidney problems
