Renal disease Flashcards
1. Give an overview of kidney functioning 2. Knowledge of pathogenesis, clinical features and management of the following - Acute renal failure - Chronic renal disease Nephrotic syndrome 3. Knowledge of renal dialysis and transplantation 4. Knowledge of relevance of renal diseases to dentistry
What are the specialised functions of the kidney
- Excretion of metabolites and drugs
- Regulation of body fluid and electrolyte balance
- Regulation of acid-base balance
- Endocrine functions
Important in vitamin D activation
How does the kidney regulate body fluid and electrolyte balance
It is made of nephrons where filtration of small molecules and ions from blood occurs - the useful materials (glucose, amino acids) are selectively reabsorbed
Urine waste is formed which is passed through the ureter to be stored in the bladder before excretion via urethra
What happens in the PCT
- actively reabsorbs glucose, amino acids, uric acid, inorganic salts
- active transports Na controlled by Angiotensin II
- active transports of phosphate surpassed by PTH
- water follows by osmosis
What happens in the LoH
Water continues to leave by osmosis
What happens in the DCT
More Na is reabsorbed by active transport and more water leaves by osmosis
What happens in the CT
Final adjustment of body Na and water content via ADH and aldosterone
Outline how RAAS controls renal endocrine function
Renin-Angiotensin-Aldosterone System
- Drop in BP is detected in kidneys
- Renin is released
- In the liver this converts Angiotensinogen to Angiotensin I
- In the lung Angiotensin I is converted to Angiotensin II by Angiotensin-converting enzyme
- This causes increase in blood pressure and aldosterone release from the adrenal cortex which increases salt retention to further increase blood pressure
Outline how the kidney is involved in the erythropoietin mechanism
Stimulant = hypoxia due to low RBC count, decreased amount of Hb, decreased oxygen availability
- Reduction in blood oxygen levels causes the kidney to release erythropoietin
- This stimulates red bone marrow
- Enhanced erythropoiesis increases RBC count
- This increases the oxygen carrying capacity of blood
- Normal blood oxygen levels maintained
What are the pre-renal factors for renal failure
- Hypotension due to haemorrhage/server burns
- Renal thrombosis
- Sepsis
- Drugs causing renal shutdown (NSAIDs + ACE inhibitors)
What are the renal factors for renal failure
- Antibiotics: gentamicin, amphotericin, streptomycin
- Analgesic overdose: aspirin, NSAIDs, paracetamol
- Multiple organ failures due to trauma/ sepsis
- Interstitial nephritis
What are the post-renal factors for renal failure
Obstructed urine flow
What is acute renal failure
It is a medical emergency that may lead to confusion, seizures and coma which is managed by dialysis
It occurs more commonly in patients that are hospitalised and those in critical care
What is chronic kidney disease
Non specific disease with several causes characterised by kidney damage/reduction in GFR (<90ml/min) for 3 or more months
It results in progressive loss of renal function (early = no symptoms, mild = GFR 60-80), moderate IIIa = GFR 45-59, IIIb = GFR 30-44, severe = GFR 15-29, end-stage = GFR <15ml/min)
What are the common causes of chronic kidney disease
- Long standing hypertension
- Diabetes mellitus
- Chronic pyelonephritis
- Chronic glomerulonephritis
- Polycystic renal disease
- Urinary tract obstruction
- Renal artery stenosis
What are the less common causes of chronic kidney disease
- Systemic Lupus erythematosus
- Amyloid (protein deposition in organs)
- Multiple myeloma
- Gout
- Lead poisoning
- Long term drug use: analgesics, Goldmans penicillamine, cyclosporine
What are the clinical features of chronic kindey disease (blood and immune)
Often symptomatic early on and symptoms manifest when kidney function is <25%
- Anaemia (due to toxic bone marrow suppression and decreased erythropoietin)
- Purpura/ Bleeding tendencies (abnormal platelet production, defective vWF, decreased thromboxane which normally aids platelet aggregation)
- Lymphopenia (incenses susceptibility to infections)
What are the clinical features of chronic kindey disease (metabolic)
- Increases nitrogenous compounds (azotaemia/uraemia)
- Renal osteodystrophy due to phosphate retention which deceases plasma calcium causing renal osteolytic lesions where the calcium will be depleted from bone which will increase PTH to regulate the calcium levels causing secondary hyperparathyroidism
- Deficiency of active vitamin D
- Polyuria, polydipsia, glycosuria
What are the clinical features of chronic kindey disease (gastrointestinal)
- anorexia
- nausea and vomiting
Due to toxic accumulation of urea and creatine which decreases appetite
What are the clinical features of chronic kindey disease (neuromuscular)
- headaches
- confusion
- sensory disturbances
- tremours
- peripheral neuropathy
What are the clinical features of chronic kindey disease (cardiovascular)
- hypertension
- congestive cardiac failure (RAAS affected; no renin produced which causes hypotension)
- atheroma
- peripheral vascular disease
What are the clinical features of chronic kindey disease (dermatological)
- puritis
- bruising
- infections
Puritis and bruising due to affected platelet function and infections occur due to lymphopenia
What investigations are done for chronic kidney disease
- Urine examination (red cell casts, white cell casts, irate crystals)
- FBC (less RBC = anaemia, impaired platelet function = greater bleeding time)
- Biochemistry (increased urea, creatine, potassium, metabolic acidosis, phosphate, PTH, decreased calcium)
Outline managements for chronic kidney disease
Aim = slow down disease progression
Anaemia - erythropoietin (Epoietin)
Hypertension - ACE inhibitors (Captopril)
Fluid retention - diuretics
Hyperphosphataemia - calcium carbonate
Metabolic acidosis - sodium bicarbonate
High cardiovascular risk - aspirin, statins, stop smoking
Hypocalcemia - calcium/ vit D3 supplements (prevents osteolytic complications)
What is renal dialysis
Indicated in end stage renal failure to remove metabolites and XS water; can either be peritoneal dialysis or haemodialysis
What are the disadvantages of renal dialysis
- Adverse effects due to rapid/XS fluid removal include
- hypoxaemia, haemolysis, hypotension
- cramps, febrile reactions, cardiac arrhythmias - Long term adverse effects include
- ischaemic heart disease
- aortic valve calcification
- dialysis related neuropathies
What is peritoneal dialysis
Where the peritoneal membrane acts as a natural semi-permeable membrane - this is less efficient but can be done more frequently at home/travelling and is easy
It makes patients more prone to peritonitis
What is haemodialysis
Vascular access is needed and infusion lines are used via arteriovenous fistulas (shunt in skin of arm) - the patient is dialysed 3 times a week for 3 hours
What is renal transplantation
It is indicated in patients with end stage renal disease, typically done in children and patients with diabetic nephropathy - transplanted kidney is sited in right iliac fossa and the old kidney remains; patient is put on life-long immunosupression (cyclosporin, azathioprine, corticosteroids) to prevent graft rejection - this also increases risk of infection, malignant and ischaemic heart disease
Outline the dental relevance for chronic kidney disease
- Treatment should be done day after dialysis as Heparin will wear off (short half-life) and maximal effects of dialysis
- Ensure careful haemostasis during surgical procedures
- Haemodialysis can predispose to blood borne viruses (Hep B + C)
- Odontogenic infection should be treated promptly because patient is on immunosuppressants (transplanted)
- Avoid fluorides, apirin and NSAIDs as will accumulate in body and prescription drugs need to be adjusted by physician
- LA is safe unless there is severe bleeding tendency
- Avoid arteriovenous fistulas arm for IV canulation and venipuncture to minimise fistula infection and thrombophlebitis
- Patients on steroids need steroid cover as adrenal gland cannot respond to produce steroids (avoids addisonian crisis)
What dental complications can occur in patients with chronic kidney disease
Renal osteodystrophy secondary to hyperparathyroidism presenting in the mouth as
- loss of lamina dura on intraoral radiographs
- brown tumours on gingiva
- osteomalacia
Which immunosupressant can cause dental complications
Cyclosporine is given for kidney transplant patients and this increases risk of gingival hyperplasia and tuberculosis
What is nephrotic syndrome
- Glomerular damage resulting in triad of
1. Massive proteinuria
2. Hypoalbuminaemia
3. Oedema - Severe hyperlipidaemia (hypercholesterolaemia)
What are the major risk factors for nephrotic syndrome
- Diabetic nephrophathy
- Systemic lupus erythematosus (SLE)
- Amyloidosis
Other risk factors
NSAIDs, penicillamine, anti-TNF, gold
HIV, hepatitis B + C, malaria
What are the clinical features of nephrotic syndrome
- Facial and pedal oedema
- Ascites (fluid retention in abdomen)
- Weight gain due to fluid retention
- Poor nutrition and loss of appetite
- Fatigue
What are the dental relevant clinical features of nephrotic syndrome
- High blood pressure
- Increased infection risk with S. pneumonia, H. influenzas due to loss of IgG in urine
- Loss of cholecalciferol binding proteins causing Vit D deficiency
- Loss of antithrombin II and increased clotting factors causing hyper coagulability and thrombosis
- Can lead to acute kidney injury or kidney disease
- Long-term corticosteroid therapy is also problematic
How is nephrotic syndrome diagnosed
- Urinalysis - hyperproteinuria
- Blood test - hypoalbuminaemia, hypoproteinaemia, urea and creatine for kidney function
- Kidney needle biopsy
Outline treatments for nephrotic syndrome
- BP medications: ACE inhibitors, ARBs to reduce BP and protein loss in urine
- Diuretics: control oedema
- Statins: reduce cholesterol
- Anticoagulants: prevents clots
- Immunosupressants: decrease inflammation accompanying conditions causing NS
