ELFH: Renal Problems and Dental Care Provision

Question 1

Functional structure of the kidneys?

Answer 1

nephron

Question 2

how does fluid arrive in the kidney?

Answer 2

afferent arteriole a branch of the renal artery

Question 3

where does the afferent arteriole enter the kidney?

Answer 3

Arriving in the knotted vessel structure known as the glomerulus

Question 4

How does fluid squeeze out of the permeable glomerulus?

Answer 4

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.

Question 5

where does fluid travel before proximal convoluted tubule?

Answer 5

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

Question 6

what acts as a filter to larger molecules before entering the proximal convoluted tubule?

Answer 6

This glomerular basement membrane acts as a filter allowing only particles of <40KDa through.

Question 7

does the fluid in the nephron/kidney require good pressure?

Answer 7

YES

The fluid requires a good pressure, thus an adequate renal blood and glomerular capillary blood flow

Question 8

What interprets blood flow of the nephron?

Answer 8

Interruption of the blood flow is recognised by specialised cells adjacent to the glomerulus known as the juxta-glomerular apparatus

Question 9

Where are the majority of fluid and electrolytes reabsorbed?

Answer 9

As the fluid passes along the proximal convoluted tubule the majority of the fluid and electrolytes are reabsorbed.

Question 10

Where is the fine tuning of potassium, hydrogen and water regulated?

Answer 10

On reaching the distal convoluted tubule the specific elimination of potassium, hydrogen ions and water is regulated further.

Question 11

where is final urine?

Answer 11

collecting ducts

Question 12

when is flow of fluid to the kidneys reduced?

Answer 12

e.g. hypotension due to hypovolaemia (reduced fluid volume)

Question 13

What happens to reabsorption and excretion in the kidney when flow of fluid to the kidney is reduced?

Answer 13

the flow of fluid through the kidney will reduce and the reabsorption of fluid will increase and excretion will reduce.

Question 14

Can you list the various functions of the kidneys?

Answer 14

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

Question 15

The following signs and symptoms may indicate renal disease?

Answer 15

dysuria
polyuria and nocturia
oliguria
proteinuria
haematuria
glycosuria

Question 16

polyuria; what is it and what can cause it?

Answer 16

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).

Question 17

oliguria; what is it and what can cause it?

Answer 17

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

Question 18

proetinuria; what is it and what can cause it?

Answer 18

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)

Question 19

Haematuria? WHAT IS IT AND WHAT CAN CUASE IT?

Answer 19

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.

Question 20

Glycosuria; what is it and what can cause it?

Answer 20

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.

Question 21

dysuria; what is it and what can cause it?

Answer 21

Pain on micturition.

Consider inflammation in bladder (cystitis), genitals or urethra, due to bacteria, chlamydia trachomatis and Neisseria gonorrhoea.

Question 22

nocturia; what is it and what can cause it?

Answer 22

Nocturia means the need to get up in the night to urinate. Consider prostatic enlargement.

Question 23

time scale of acute renal failure?

Answer 23

can occur quickly over days to weeks

Question 24

timescale of chronic renal failure?

Answer 24

develop over months or years

Question 25

pre-renal cause of ARF?

Answer 25

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.

Question 26

renal failure of ARF?

Answer 26

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.

Question 27

post-renal cause of ARF?

Answer 27

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.

Question 28

symptoms of ARF?

Answer 28

- 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

Question 29

what concentration of plasma urea does ARF become obvious?

Answer 29

under 40mmol/L

Question 30

What blood changes would you expect to find in a patient with acute renal failure (ARF)?

Answer 30

- elevated urea and electrolytes (particularly the potassium) - deranged liver function test (hepatic-renal syndrome) - arterial blood gases: acidosis (pH <7.35), decreased bicarbonate - full blood count: lowered hemoglobin and elevated white cell count

Question 31

tx for ARF?

Answer 31

- 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

Question 32

How can high potassium be treated urgently?

Answer 32

- 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

Question 33

cause of CRF?

Answer 33

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

Question 34

symptoms of CRF?

Answer 34

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.

Question 35

calcium probelms and CRF?

Answer 35

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).

Question 36

tx for CRF?

Answer 36

- 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

Question 37

3 main types of dialysis?

Answer 37

haemodialysis haemofiltration peritoneal dialysis

Question 38

main complications of dialysis?

Answer 38

- 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

Question 39

Complications of immunosuppression?

Answer 39

- 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

Question 40

Immunosuppression is required which will involve...?

Answer 40

steroids azothioprine ciclosporin tacrolimus antilymphocyte globulin is increasingly used mycophenolate anti Il-12 receptor

Question 41

All patients will be subject to infections and risk of malignancy development. There can also be signifcant complications...?

Answer 41

- 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

Question 42

Can you list any potential oral manifestations of CRF?

Answer 42

thrush parotitis oral ulceration occasional lysis of the jaw bones characteristic oral odour due to ammonia in breath

Question 43

General guidelines for drug prescribing include with pt with renal failure?

Answer 43

- 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

Question 44

The following are key points to remember when dealing with patients experiencing renal problems: (10)

Answer 44

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

Question 45

Answer 45

A: periodontal disease

Question 46

Answer 46

A: NSAIDs B: midazolam