ELFH: Renal Problems and Dental Care Provision Flashcards
Functional structure of the kidneys?
nephron
how does fluid arrive in the kidney?
afferent arteriole a branch of the renal artery
where does the afferent arteriole enter the kidney?
Arriving in the knotted vessel structure known as the glomerulus
How does fluid squeeze out of the permeable glomerulus?
because of the increased pressure, the fluid is squeezed out of the permeable glomerular vessels to make the early glomerular filtrate, which forms the basis of urine.
where does fluid travel before proximal convoluted tubule?
This fluid has to pass through a basement membrane to enter the Bowman’s capsule before the fluid makes its journey down to the proximal convoluted tubule
what acts as a filter to larger molecules before entering the proximal convoluted tubule?
This glomerular basement membrane acts as a filter allowing only particles of <40KDa through.
does the fluid in the nephron/kidney require good pressure?
YES
The fluid requires a good pressure, thus an adequate renal blood and glomerular capillary blood flow
What interprets blood flow of the nephron?
Interruption of the blood flow is recognised by specialised cells adjacent to the glomerulus known as the juxta-glomerular apparatus
Where are the majority of fluid and electrolytes reabsorbed?
As the fluid passes along the proximal convoluted tubule the majority of the fluid and electrolytes are reabsorbed.
Where is the fine tuning of potassium, hydrogen and water regulated?
On reaching the distal convoluted tubule the specific elimination of potassium, hydrogen ions and water is regulated further.
where is final urine?
collecting ducts
when is flow of fluid to the kidneys reduced?
e.g. hypotension due to hypovolaemia (reduced fluid volume)
What happens to reabsorption and excretion in the kidney when flow of fluid to the kidney is reduced?
the flow of fluid through the kidney will reduce and the reabsorption of fluid will increase and excretion will reduce.
Can you list the various functions of the kidneys?
1) elimination of waste (urea)
2) maintenance of levels of electrolyte (sodium and potassium), blood volume and thus blood pressure
3) control of electrolytes, pH and calcium
4) endocrine functions:
- secretion of erythropoietin
- release of renin-angiotensin
- vitamin D metabolism
The following signs and symptoms may indicate renal disease?
dysuria
polyuria and nocturia
oliguria
proteinuria
haematuria
glycosuria
polyuria; what is it and what can cause it?
Polyuria is passing more than 3 litres of urine in a day, which may occur in osmotic diuresis such as glycosuria or chronic renal failure (inability to reabsorb filtered fluid).
oliguria; what is it and what can cause it?
Urine output less than 300ml in a day.
Causes include:
- pre-renal: low blood volume or pressure (reduced glomerular filtration)
- renal: intrinsic renal disease such as acute or chronic renal failure
- post-renal: obstruction
proetinuria; what is it and what can cause it?
Urine usually contains very small traces of protein (max 200mg/day) as the glomerular basement membrane prevents proteins entering into the tubules and the proximal convoluted tubules will reabsorb any that do pass through. Proteinuria may be due to:
- excess plasma proteins (small) produced, for example, multiple myeloma
- glomerular membrane disease (allowing the proteins to escape especially albumin, for example, diabetes)
- damage to the proximal convoluted tubule (usually results in loss of other constituents such as glucose, phosphate)
Haematuria? WHAT IS IT AND WHAT CAN CUASE IT?
Blood in the urine.
Can occur at any site; glomerulus, renal pelvis, bladder, prostate urethra.
Causes include bleeding disorders, renal trauma, gomerulonephritis, carcinoma of kidney, prostate or bladder, stones, infection, autoimmune inflammation and prostate hypertrophy.
Glycosuria; what is it and what can cause it?
Glycosuria is glucose in the urine. In normal health glucose is not detected.
The most common cause of glycosuria is diabetes mellitus. In the rare circumstances it can be due to abnormal glucose filtering by the kidney.
dysuria; what is it and what can cause it?
Pain on micturition.
Consider inflammation in bladder (cystitis), genitals or urethra, due to bacteria, chlamydia trachomatis and Neisseria gonorrhoea.
nocturia; what is it and what can cause it?
Nocturia means the need to get up in the night to urinate. Consider prostatic enlargement.
time scale of acute renal failure?
can occur quickly over days to weeks
timescale of chronic renal failure?
develop over months or years
pre-renal cause of ARF?
The glomerulus requires sufficient pressure to create a glomerular filtration. When either the pressure drops or the volume of blood reduces, despite autoregulatory mechanisms designed to maintain glomerular pressure (renin-angiotensin and prostaglandins), renal function will drop off.
Causes of hypovolaemia include bleeding, fluid loss, sepsis, reduced pump pressure, for example, myocardial infarction (MI) and congestive cardiac failure (CCF) and liver failure (hepatorenal syndrome).
Fluid replacement with or without diuretic stimulus is the mainstay of care.
renal failure of ARF?
Damage may affect tubules, interstitium, renal vessels or the glomerulus. The kidney is unable to concentrate urine and preserve cations.
Causes include ischaemia, toxins such as gentamicin, intravenous (IV) contrast agents, myoglobin, drug damage, renal artery thrombosis, vasculitides and glomerulonephritis.
post-renal cause of ARF?
Most common post-renal cause of acute renal failure is obstruction of the urinary outflow.
Causes to be investigated include stones, tumours, congenital abnormalities or infection.
symptoms of ARF?
- oliguria (<300ml per day), as no glomerular filtration rate (GFR) created
- uraemic-induced neurological symptoms, for example, weakness, seizures, confusion, metabolic acidosis and deep breathing (Kussmaul)
- skin pallor, pigmentation and pruritis
- anaemia (reduced erythropoetin), reduced GFR, raised urea and creatinine, raised potassium
- pulmonary oedema (fluid overload as no GFR and no urinary output) high blood pressure, breathlessness, hiccoughs (uraemia)
- nausea, vomiting
- impaired platelet function exacerbates bleeding issues
what concentration of plasma urea does ARF become obvious?
under 40mmol/L
What blood changes would you expect to find in a patient with acute renal failure (ARF)?
- elevated urea and electrolytes (particularly the potassium)
- deranged liver function test (hepatic-renal syndrome)
- ## arterial blood gases: acidosis (pH <7.35), decreased bicarbonatefull blood count: lowered hemoglobin and elevated white cell count
tx for ARF?
- providing urgent support
- oxygenation
- maintain and/or reestablish circulatory pressure and volume
- monitor and treat urgently hyperkalaemia (6.0mmol/L), which if not treated will induce life-threatening cardiac arrythmias
How can high potassium be treated urgently?
- IV calcium gluconate
- IV insulin (acts on glucose potassium cotransporter cell membrane pumps)
- oral calium resonium (chelates potassium)
dialysis if:
hyperkalaemia (>6.5mmol/L)
acidosis
encephalopathy
pulmonary oedema
percarditis
cause of CRF?
Underlying the failure is a gradual fibrosis of the glomerulus, tubules or the vasculature leading to fibrosis and scarring which will prevent the kidney from functioning.
Other causes include:
hypertension
polycystic disease (Figure 1)
glomerulonephritis
interstitial nephritis
symptoms of CRF?
anaemia
- Reduced erythropoeitin, acidosis inhibiting the bone marrow function and reducing red cell survival, reduced iron and folate.
calcium problems
neurological issues
- Uraemia may cause motor (weakness) or sensory (numbness) disturbances.
- autonomic nervous sytem changes may lead to loss of sphincter control leading to diarrhoea and blood pressure sensor control leading to postural hypotension.
- Patients can also suffer from confusion, fitting and even fall into a coma.
bleeding
- Platelet abnormailty due to acidosis and bone marrow dysfunction.
skin problems
- Pigmentation and pruritis.
GIT
- Anorexia and vomiting.
renal function
- Drug excretion, fluid balance.
cardiac problems
- Hypertension due to renin-angiotensin release, fluid overload (increased blood volume, increased venous return and thus increased stroke volume leading to increased cardiac output and hence increased blood pressure). Also a risk of possible cardiomyopathy and dysfunctional lipid metabolism.
calcium probelms and CRF?
Termed renal osteodystrophy, reduced activation of vitamin D3 (1 hydroxylation), which reduces absorption of calcium from the gut, reduces calcium mobilisation by bone osteoclasts and increases renal loss of calcium, leading to overall calcium level reduction and increased phosphate retention. This stimulates the parathyroid glands to release parathyroid hormone (PTH).
PTH released leads to osteoclast bone resorption which leads to skeletal challenges, such as osteomalacia. This activation of the parathyroid glands is termed as secondary hyperparathyroidism (secondary to renal disease). When the renal issues are treated, the PTH secretion should return to normal. However if the PTH continues to be secreted, this becomes known as tertiary hyperparathyroidism (autonomous PTH secretion hyperparathyroidism).
tx for CRF?
- protein, sodium and potassium dietary restriction
- control of blood pressure and restriction of fluid if there is fluid overload
- phosphate dietary control and vitamin D analogues; may require parathyroidectomy
- recombinant human erythropoietin for anaemia but beware hypertension
- acidosis managed with monitoring and bicarbonate
EVENTUALLY DIALYSIS
3 main types of dialysis?
haemodialysis
haemofiltration
peritoneal dialysis
main complications of dialysis?
- cardiovascular disease (atheroma deposition)
- sepsis (commonly Staphylococcus aureus)
- amyloid deposition due to beta microglobulin polymerisation (part of major histocompatibility complex (MHC) structures usually removed by kidney but not dialysis) leading to carpal tunnel syndrome and joint pain
Complications of immunosuppression?
- opportunistic infections
- high blood pressure
- tumour development, for example, skin and lymphoma
- recurrence of renal disease
- dentists should remember the risks of hepatitis B and C
- treat infections aggressively, discuss antibiotic cover with clinician
- look for drug-related side effects
- dentists must always give consideration to changes in drug metabolism
Immunosuppression is required which will involve…?
steroids
azothioprine
ciclosporin
tacrolimus
antilymphocyte globulin is increasingly used
mycophenolate
anti Il-12 receptor
All patients will be subject to infections and risk of malignancy development. There can also be signifcant complications…?
- ciclosporin; gingival hyperplasia, diabetes and high blood pressure
- tacrolimus; hair loss, high blood pressure and kidney damage
- azothioprin; inhibits white cell synthesis and hair loss
- mycophenalate; can cause significant vomiting and diarrohea, also reduced white cell number
- steroids; complications are as expected including high blood pressure, osteoporosis, opportunistic infections, diabetes, mood changes, skin fragility and cushinoid shape changes
Can you list any potential oral manifestations of CRF?
thrush
parotitis
oral ulceration
occasional lysis of the jaw bones
characteristic oral odour due to ammonia in breath
General guidelines for drug prescribing include with pt with renal failure?
- avoid NSAIDS (general medical practitioners should avoid angiotensin-converting enzyme (ACE) inhibitors)
- reduce doses of amoxicillin, although metronidazole is unaffected
- lignocaine is safe (Figure 1)
- avoid midazolam
- only prescribe short courses of paracetamol
The following are key points to remember when dealing with patients experiencing renal problems: (10)
1) forewarned is forearmed, thus a good medical history should be obtained as well as keeping the signs and symptoms in mind
2) prevention is important with dietary and oral hygiene instruction, also regular follow-up
3) use a local anaesthetic
4) infections need prompt and thorough treatment
5) check if on dialysis if bleeding problems exist
6) check drug doses with the supervising medical team
7) remember the increased risks of high blood pressure
8) radiolucencies on x-rays may be related to bone resorption
9) fit treatment around the dialysis but avoid the same day as they will have been anti-coagulated
10) consider the increased hepatitis B and C risks
A: periodontal disease
A: NSAIDs
B: midazolam
