Renal Flashcards
The epithelial sodium channel located in the collecting duct is regulated by which of the following?
* a)Adrenocorticotrophic hormone (ACTH).
* b)Amiloride.
* c)Aldosterone.
* d)Cyclic AMP.
* e)Renin
The collecting duct only reabsorbs 2% of filtered Na+ (most is reabsorbed in the proximal tubule (50%) and ascending limb of the loop of Henle (40%).
Na is reabsorbed via aldosterone sensitive Na+ channels in exchange for K+
Note: spironolactone binds to aldosterone receptor causing dieresis and K+ sparing.
Aldosterone sensitive channels also present in distal tubule.
A: ACTH. Stimulates the adrenal cortex.
B: Amiloride. A sodium channel blocker that directly inhibits the entry of sodium into the sodium channels of the luminal membrane thus reducing the effectiveness of the Na+/K+ ATPase - potassium sparing.
D: Cyclic AMP. Aldosterone binds a mineralocorticoid receptor protein and diffuses to the nucleus effecting changes in nuclear transcription of proteins (membrane transport proteins and enzymes). It also has been shown to rapidly increase cAMP levels in vascular smooth muscle and the epithelial cells of the renal collecting tubules, the physiological importance of this is not yet well understood.
E: Renin. An enzyme released by the JG cells in response to low arterial blood pressure. Cleaves angiotensinogen to Angiotensin I.
The correct answer is C.
A 16-year-old post pubertal boy has chronic renal failure with a serum creatinine of 300 μmol/L due to glomerulonephritis. Two years ago his creatinine was 100 μmol/L and one year ago it was 200 μmol/L. He wants to complete his schooling in two years time before undergoing pre-emptive living related transplantation. He is growing on the 25th percentile for height and the 10th for weight (having gained height but not weight in the last year). His blood pressure is 140/105 mmHg and he has 2.0 g per day of proteinuria. His dietary protein content is 2 g/kg/day.
His serum chemistry is:
sodium 140 mmol/L [135-150];
potassium 4.0 mmol/L [3.5-5.0];
chloride 105 mmol/L [90-110];
urea 45 mmol/L [<6];
creatinine 0.3 mmol/L [0.05-0.12];
haemoglobin 90 g/L [120-150];
calcium 2.4 mmol/L [2.26-2.56];
phosphate 2.6 mmol/L [0.94-1.37];
parathyroid hormone 70 pg/ml [2-7].
Which one of the following will have no effect on the progression to end-stage renal failure?
* a)Angiotensin converting enzyme inhibition.
* b)Correction of anaemia using erythropoietin.
* c)Correction of hyperphosphataemia.
* d)Energy replete, protein restricted diet.
* e)Reducing blood pressure.
Main abnormalities are anaemia and high phosphate
Progression from chronic kidney disease to ESRD can be slowed by the aggressive control of diabetes, hypertension and proteinuria.
Aggressively manage anaemia and renal osteodystrophy (hyperphospataemia, hypocalcaemia, hyperparathyroidism) before renal replacement therapy.
A. Angiotensin-converting enzyme (ACE) inhibitors (enalapril, lisinopril) are the antihypertensive medication of choice in all children with proteinuric renal disease, because of their potential ability to slow the progression to end-stage renal disease.
C. Hyperphosphatemia may increase progression of disease by leading to calcium-phosphate deposition in the renal interstitium and blood vessels.
D. Proteinuria itself may contribute to renal functional decline, as evidenced by studies that have shown a beneficial effect of reduction in proteinuria. Proteins that traverse the glomerular capillary wall may exert a direct toxic effect and recruit monocytes/macrophages, enhancing the process of glomerular sclerosis and tubulointerstitial fibrosis.
E. Uncontrolled hypertension may exacerbate disease progression by causing arteriolar nephrosclerosis as well as by increasing the hyperfiltration injury.
The correct answer is B.
Which of the following investigations is most suitable?
* Renal ultrasound
* Intravenous urography (IVU)
* Renal arteriography
* Dimercaptosuccinic acid (DMSA)
* Micturating Cystourethrogram (MCUG)
* Mercaptoacetlytriglyine (MAG3)
* Magnetic Resonance Urography (MRU)
* Diethlenetriaminepenta-acetic acid (DTPA)
A five-year-old with suspected vesicoureteral reflux (VUR).
Correct answer:Micturating Cystourethrogram (MCUG)
Explanation:
MCUG is used to look for VUR. It will give the appearance of the bladder and urethra outline – which can reveal posterior urethral valves in Males. MCUG and VCUG are the same investigation. M=micturating. V=voiding. These investigations are performed less often now as there seems to be no clear benefit from detecting VUR in this age group unless there is a concern about obstructive uropathy.
Which of the following investigations is most suitable?
* Renal ultrasound
* Intravenous urography (IVU)
* Renal arteriography
* Dimercaptosuccinic acid (DMSA)
* Micturating Cystourethrogram (MCUG)
* Mercaptoacetlytriglyine (MAG3)
* Magnetic Resonance Urography (MRU)
* Diethlenetriaminepenta-acetic acid (DTPA)
An eight-yearoold presents with multiple café au lait and axillary freckling presents with hypertension.
Correct answer:Renal arteriography
Explanation:
This scenario alludes to a child with neurofibromatosis who is at increased risk of renal artery stenosis (RAS) and should be investigated with renal arteriography as gold standard. Doppler renal ultrasound may be done as first line but is not as sensitive nor specific. In adults, RAS is most commonly caused by atherosclerosis. In children, fibromuscular dysplasia is the leading cause.
NOTE: THE MOST COMMON CAUSE OF HTN IN NF IS STILL ESSENTIAL HTN (this is another question that comes up)
Which of the following investigations is most suitable?
* Renal ultrasound
* Intravenous urography (IVU)
* Renal arteriography
* Dimercaptosuccinic acid (DMSA)
* Micturating Cystourethrogram (MCUG)
* Mercaptoacetlytriglyine (MAG3)
* Magnetic Resonance Urography (MRU)
* Diethlenetriaminepenta-acetic acid (DTPA)
A seven-year-old with Wilms tumour awaiting surgery.
Correct answer:Magnetic Resonance Urography (MRU)
Explanation:
MRU gives a more detailed assessment of renal anatomy which is particularly helpful to surgeons. When a child initially presents with an abdominal mass, a renal ultrasound is done. Once a mass is seen and Wilms is suspected, more detailed imaging is required.
Ryan is a 15-year-old who you review as the admitting registrar for general paediatrics. He is an otherwise well, immunised child who has been referred with acute kidney injury (AKI).
Ryan has had a 48-hour history of profuse watery diarrhoea and vomiting, with up to 15 loose motions today, non-bloody. His examination is unremarkable.
Initial results are as shown:
VBG: pH 7.34, pCO2 30, HCO3 15.6, Na 141, K 3.9, Cl 109, gluc 7.4, lactate 2.3
Na 144, K 4.1, Cl 104, HCO3 19, urea 17.6, creat 181, Hb 175, WCC 11.5, plat 307, neut 9.1, lymph 0.9
Following a 1L bolus of normal saline his repeat VBG shows:
pH 7.27, CO2 40, HCO3 18, Na 144, K 4.1, Cl 111, gluc 7.6, lactate 2.3
Urine microscopy:
white blood cells (x106/L) 10-100
red blood cells (x106/L) >100
epithelial cells (x106/L) <10
Moderate hyaline casts
Occasional granular casts
These results are most consistent with:
* a)rotavirus gastroenteritis and enterococcus urinary tract infection (UTI).
* b)acute tubular necrosis (ATN).
* c)rotavirus gastroenteritis.
* d)haemolytic uraemic syndrome.
* e)rotavirus gastroenteritis and glomerulonephritis.
This patient has pre renal AKI secondary to hypovolaemia from profuse vomiting and diarrhoea. This is reflected in the increase in sodium as although glomerular filtration rate is reduced, the kidneys avidly reabsorb sodium and water leading to oliguria. A high anion gap metabolic acidosis is common (demonstrated in the second VBG), and is secondary to the impaired renal excretion of acid, and reabsorption and regeneration of bicarbonate.
A: It is plausible to obtain a UTI from difficulties with hygiene associated with acute gastroenteritis. The urine microscopy results are consistent with UTI. Hyaline casts can be observed with small volumes of concentrated urine.
B: “Muddy brown” or haem-granular casts are characteristic of ATN. Desquamation of tubular epithelium in ATN also usually results in renal tubular epithelial cells. Calculating the fractional excretion of sodium or observing improvement in serum creatinine and urea following a fluid challenge would distinguish between pre renal AKI and ATN. The history makes pre renal AKI more likely than ATN in this case.
C: Rotavirus gastroenteritis explains pre renal AKI, but not the urine microscopy results.
D: Haemolytic uraemic syndrome is a renal cause of acute kidney injury. The most common cause of renal AKI is prolonged hypoperfusion. Microangiopathic haemolytic anaemia with thrombocytopenia in the setting of AKI is diagnostic for haemolytic uraemic syndrome.
E: This option suggests a mix of pathologies, prolonged hypoperfusion from rotavirus gastroenteritis and glomerular pathology. This is unlikely, particularly in the absence of red blood cell casts which are associated with glomerular haematuria and an underlying glomerulonephritis.
The correct answer is A.
Choose the most appropriate diagnosis for the following scenarios
* Dent disease
* Barter syndrome
* Wilson disease
* Von Gierke disease
* Homocystinuria
* McCune-Albright syndrome
* Lowe Oculocerebrorenal syndrome
* Cystinosis
Q1:
An eight-year-old boy presents with polyuria, microscopic haematuria and abdominal pain. He is found to have renal calculi. Further investigation reveals a mutation in the CLCN5 gene.
Correct answer:Dent disease
Explanation:
Dent disease is also known as X-linked recessive nephrolithiasis. Children with Dent disease present with polyuria, microscopic haematuria, proteinuria or kidney stones. 75% of patients develop kidney stones. Most cases of Dent disease are caused by mutations in theCLCN5genethat inactivates a voltage-gated chloride transporter named CLC-5. Some cases are associated with mutations in theOCRL1gene, which is also the gene mutation associated with Lowe oculocerebrorenal syndrome.
Choose the most appropriate diagnosis for the following scenarios
* Dent disease
* Barter syndrome
* Wilson disease
* Von Gierke disease
* Homocystinuria
* McCune-Albright syndrome
* Lowe Oculocerebrorenal syndrome
* Cystinosis
A four-month-old boy has vitamin D resistant rickets and renal calculi. Cysteine levels in leukocytes are elevated.
Correct answer:Cystinosis
Explanation:
Cystinosis is a lysosomal storage disease. Cysteine accumulates in organs and tissues, leading to severe organ dysfunction. Children appear normal at birth but present with renal problems at 3-6 months of age. They will often have vitamin D resistant rickets at presentation, secondary to phosphate wasting. Diagnosis is confirmed by measuring high levels of cysteine in leukocytes or fibroblasts. Homocystinuria is a different entity but is often confused with cystinosis because of the similar name. Children with homocystinuria have Marfanoid habitus and are prone to thrombotic events but do not usually have renal problems.
Choose the most appropriate diagnosis for the following scenarios
* Dent disease
* Barter syndrome
* Wilson disease
* Von Gierke disease
* Homocystinuria
* McCune-Albright syndrome
* Lowe Oculocerebrorenal syndrome
* Cystinosis
A 14-year-old boy with liver disease, seizures and renal calculi.
Correct answer:Wilson disease
Explanation:
Wilson disease which usually presents with hepatic dysfunction in children. In teenagers and adults, neurological and psychiatric problems are the more common presenting complaint. Kaiser-fleischer rings are seen in 50% of patients with liver disease and nearly 100% of patients with neurological involvement. A less well known clinical feature of Wilson disease is that is can lead to distal renal tubular acidosis which results in kidney stones. Von Gierke disease is also known as glycogen storage disease type 1a. Clinical features include hepatomegaly, seizures (secondary to hypoglycaemia), renal calculi, poor growth and doll-like facies. It presents in infancy.
What birth defect would you expect with the use of Irbesartan after 20 weeks of pregnancy?
- Limb defects
- MCDK
- PDA
- Renal insufficiency
A: Limb defects are a complication of ACE-I/ARB use in pregnancy, affecting around 17% of neonates exposed after 20 weeks.
B: MCDK is not associated with ACE-I/ARB use, but is linked to anticonvulsant use in pregnancy.
C: PDA is an uncommon complication of ACE-I/ARB exposure in utero.
D: Renal insufficiency, sometimes requiring dialysis, is the most common complication of intrauterine ACE-I/ARB exposure.
The correct answer is D.
Which of the following would not be associated with increased renin release?
- increased beta-1 adrenergic activation
- increased ANP
- Decreased distal tubule sodium
- Decreased afferent arteriolar pressure
The RAAS system is essential for the regulation of blood pressure and fluid balance.
A: Beta-1 adrenergic activation (via cardiac and arterial baroreceptors) stimulates renin release.
B: ANP, stimulated by atrial stretch receptors, inhibits renin release.
C: Decreased distal tubule sodium delivery, detected by the macula densa, stimulates renin release.
D: Decreased afferent arteriolar pressure, detected by local baroreceptors, increases renin release from the juxtaglomerular cells.
The correct answer is B.
A child develops fever, abnormal liver function tests and diarrhoea on day 60 post-renal transplantation.
What is the most likely cause of these findings?
* a)Acute renal rejection.
* b)Cytomegalovirus infection.
* c)Graft-versus-host disease.
* d)Post-transplant lymphoproliferative disease.
* e)Tacrolimus toxicity.
Infection is the most common cause of first-year post-transplantation mortality and morbidity.
During the first post-transplantation year, 40-80% of transplant recipients experience at least one infection; however, these numbers are decreasing as more transplant recipients receive preoperative immunisations and take post-transplantation antibiotic prophylaxis.
Infection most commonly occurs in mucocutaneous areas (41%), the urinary tract (17.2%), and the respiratory tract (13.9%).
The most common infective agents were bacterial (45.9%), viral (40.6%), fungal (12.5%), and protozoan (1%).
CMV (31.5%),herpes simplex(23.4%), andherpes zoster(23.4%) were the most frequent viral illnesses.
Infection (32%) was the most common cause of death; pneumonias accounted for 50% of the patient deaths from infection.
Infectious agents can often be identified by the time interval from transplantation to presentation.
The first post-transplantation month is dominated by infections directly related to the surgery. These entities include urinary tract infections (Escherichia coli), line infections (Staphylococcus aureus, Streptococcus viridans), wound infections (S aureus,S viridans), and pneumonia (Streptococcus pneumoniae).
The initial 6 post-transplant months are associated with the highest levels of immunosuppression and therefore carry the greatest risk of viral and opportunistic infections. CMV is responsible for more than two thirds of febrile episodes during this period.
These patients often present with fever, malaise, lymphadenopathy, arthralgias, and myalgias.
Laboratory studies may show leukocytosis with atypical lymphocytes and mild hypertransaminasemia.
Diagnosis is based upon isolation of virus or antibody titres. Untreated CMV has been associated with a mortality rate as high as 15%.
Other opportunistic infections includePneumocystis cariniipneumonia, listeriosis meningitis, and sepsis with the organismAspergillus fumigatus.
The correct answer is B.
