Renal

Question 1

UTI - definitions

Answer 1

• Bacteriuria – there is bacteria present in the urine which can be symptomatic or asymptomatic.
• Urinary tract infection – presence of a pure growth of >10⁵ organisms per mL of fresh MSU. UTIs can be classified as lower - urethritis, cystitis and prostatitis or upper – pyelonephritis.

Question 2

UTI - classification

Answer 2

• Uncomplicated if there is normal urinary tract and function or complicated if there’s abnormal tract or function, voiding difficulty, outflow obstruction or a virulent organism e.g. S aureus.
• Recurrent is a further infection with a new organism and relapse is with the same organism.

Question 3

UTI - risk factors

Answer 3

Female, sexual intercourse, exposure to spermicide in females (by diaphragm or condoms), pregnancy, menopause, depleted host defences (e.g. immunosuppression or diabetes mellitus) or a urinary tract abnormality (e.g. obstruction, stones, catheter or malformation).

Question 4

UTI - in pregnancy

Answer 4

UTIs are common and often asymptomatic until serious pyelonephritis or premature labour ± fetal death can occur so urine should be routinely tested at all antenatal appointments.

Question 5

UTI - in catheterised patients

Answer 5

Urine is almost always infected so investigations are pointless unless patient is ill.

Question 6

UTI - organisms

Answer 6

Most commonly E coli (>70% in the community but <41% in hospital) but also Staph saprophyticus or Proteus mirabilis.

Rarer causes include Enterococcus faecalis, Klebsiella, Enterobacter and Acinetobacter species, Psuedomonas aureginosa, Serratia marascens or Staphylococcus aureus.

Question 7

UTI - symptoms

Answer 7

• Acute pyelonephritis – fever, rigors, vomiting, loin pain and tenderness and oliguria (if ARF).
• Cystitis – frequency, dysuria, urgency, strangury (strong desire), haematuria or suprapubic pain.
• Prostatitis – flu like symptoms, back ache, few urinary symptoms, swollen or tender prostate.

Question 8

UTI - signs

Answer 8

Fever, abdo or loin tenderness, foul smelling urine, distended bladder or an enlarged prostate.

Question 9

UTI - urine dipstick

Answer 9

If symptoms are present dipstick the urine and treat empirically if nitrites or leucocytes are positive while awaiting sensitivities on an MSU.

If dipstick is negative consider sending for MC+S to confirm this. Send for a lab MSU anyway if male, a child, pregnant, immunosuppressed or unwell.

A pure growth of >10⁵ organisms per mL is diagnostic.

Question 10

UTI - pyuria

Answer 10

If <10⁵ organisms per mL and >20 WBCs/mm3 the result may still be significant. It can be caused by a treated UTI <2 weeks ago, inadequately treated UTI, fastidious culture requirement, appendicitis, tubulointerstitial nephritis, caliculi, prostatitis, PKD or a tumour.

Question 11

UTI - bloods and imaging

Answer 11

• Bloods – FBC, Us and Es, CRP and blood culture if systemically unwell – known as urosepsis.
• Ultrasound, IVU or cystoscopy – consider for UTI in children, men, if failure to respond to treatment, recurrent UTI (>2/year), pyelonephritis, unusual organism or persistent haematuria.

Question 12

UTI - management

Answer 12

• Lower UTI – consider empirical treatment in otherwise healthy women with 200mg Trimethaprim BD or Nitrofurantoin for 3-6 days. If no response perform urine culture.
• Upper UTI – culture urine and give 1.5g Cefuroxime TDS IV followed by oral for 7 days.

Question 13

UTI - management in pregnancy

Answer 13

Get expert help, any bacteriuria is treated with Nitrofurantoin whether it as symptomatic or not. Urine cultures should be repeated at each antenatal visit.

Question 14

UTI - management in men

Answer 14

Often results from an anatomical or functional abnormality so should be taken seriously and referred to an urologist. Give a 2 week course of Levofloxacin (a quinolone antibiotic) and if no response consider prostatitis and give 4 weeks of treatment.

Question 15

UTI - prevention

Answer 15

Increase water intake, antibiotic prophylaxis (either continuous or post-coital), drinking 200-750mL of cranberry or lingo berry juice per day or taking oral cranberry concentrate tablets.

Question 16

GN - definition

Answer 16

A common cause of end stage renal failure in adults along with diabetes and hypertension.

They are a group of disorders where damage to the glomerular filtrating apparatus causes a leak of protein ± blood into the urine (which depends on the cause).

Patients may be asymptomatic or present with haematuria (microscopic ± red cell casts), proteinuria, renal failure or hypertension.

Question 17

GN - investigations

Answer 17

• Bloods – FBC, Us and Es, LFTs, ESR and CRP, immunoglobulins, electrophoresis, complement levels (C3 and C4), autoantibodies, ANA, ANCA, anti-ds DNA, anti-GBM and blood cultures.
• Urine – red cell casts, MC+S and Bence-Jones proteins. Can also measure 24 hr urine protein.
• Further investigations – a chest x-ray, renal ultrasound or renal biopsy may be useful.

Question 18

Nephritic syndrome - definition

Answer 18

A group of signs – haematuria (with RBC casts ± dysmorphic RBCs), proteinuria, hypertension and progressive oliguria and renal impairment – caused by disease of the glomerulus.

Question 19

GN - IgA nephropathy

Answer 19

Berger’s disease – the most common glomerulonephritis in the developed world and usually presents with macro or microscopic haematuria or occasionally with nephritic syndrome.

• Typical patient – a young man with episodic macroscopic haematuria occurring a few days after an upper respiratory tract infection e.g. pharyngitis and recovery is often rapid between attacks. There’s increased IgA which forms immune complexes and deposits on mesangial cells.
• Renal biopsy – mesangial proliferation and immunofluorescence shows deposits of IgA and C3.
• Management – the role of immunosuppression is uncertain but steroids may decrease proteinuria and slow down decline in renal function. Cyclophosphamide may also be effective.
• Prognosis – worse if male, hypertension, proteinuria or renal failure at presentation.

Question 20

GN - SLE

Answer 20

Approximately 20% of patients with lupus will have evidence of renal involvement. The mechanism can vary between vascular, glomerular or tubulointerstitial damage.

Question 21

GN - anti-GBM disease

Answer 21

Goodpasture’s disease – caused by the development of auto-antibodies to type IV collagen as essential component of the glomerular basement membrane. Type IV collagen is also found in the lung and haemoptysis may also be a feature especially in smokers.

Young males are most commonly affected but can occur at any age and gender. Presentation is with macroscopic haematuria, rapidly progressing oliguria and renal failure within days. This can be prevented with rapid early treatment – plasma exchange, corticosteroids and cytotoxics.

Question 22

GN - proliferative GN

Answer 22

Classified histologically – focal, diffuse or mesangialcapillary glomerulonephritis. The main cause is post-streptococcal glomerulonephritis occurring 1-12 weeks after a sore throat or skin infection.

A streptococcal antigen is deposited on the glomerulus causing a host reaction and immune complex formation. It usually presents with nephritic syndrome.

Renal biopsy shows an inflammatory reaction affecting mesangial and endothelial cells, immunofluorescence shows IgG and C3 deposits and ASOT (anti-streptolysin O titre) is raised.

Management is supportive and >95% completely recover.

Question 23

GN - Henoch-Schonlein purpura

Answer 23

A systemic variant of IgA nephropathy causing a small vessel vasculitis. It causes a purpuric rash on the extensor surfaces, flitting polyarthritis, scrotal and scalp swelling, abdominal pain (due to bleeding) and nephritis.

Diagnosis is usually clinical but can be confirmed with immunofluorescence for IgA and C3 in skin or renal biopsy.

Management is with steroids or cyclophosphamide for resistant cases but up to 50% can develop end stage renal failure.

Question 24

GN - rapidly progressive GN - definition

Answer 24

The most aggressive form that can lead to end stage renal failure in days. There are different causes but all have the same biopsy findings – crescents affecting most glomeruli – a proliferation of parietal epithelial cells and macrophages in Bowman’s capsule.

RPGN is classified pathologically into 3 categories:

• Immune complex disease (45%) – post-infectious, SLE, IgA nephropathy or HSP.
• Pauci-immune disease (50% of cases) – 80-90% of cases are ANCA positive – Wegener’s granulomatosis (C-ANCA), microscopic polyarteritis (P-ANCA) or Churg-Strauss.
• Anti-GBM antibody disease (5%) – 10-40% are ANCA positive – Goodpasture’s disease.

Question 25

GN - RPGN - presentation and management

Answer 25

• Clinical presentation – there are signs of renal failure and of the individual systemic diseases e.g. fever, malaise, myalgia, weight loss or haemoptysis. Massive pulmonary haemorrhage is the most common cause of death in patients who are ANCA positive.
• Management – aggressive immunosuppression with corticosteroids and cyclophosphamide.
• Prognosis – around 80% will have some improvement in renal function following treatment.