Nephrology Flashcards
What is the emergency treatment of symptomatic hyponatremia?
IV infusion of hypertonic saline (3%) at a dose of 3 mL/kg. This will raise serum sodium concentration by 3-4 mEq/L. Can repeat dose every 10-20 minutes.
Why can correcting hypernatremia too quickly cause seizures?
When you have hypernatremia, fluid shifts out of brain cells. In reponse, brain cells make idiogenic osmoles that help minimize their water loss. Creating or getting rid of these osmoles takes about 24 hours. If you correct too quickly, water moves back into the brain cells and you get cerebral edema.
What is the maximum rate of sodium correction in hypernatremia?
Don’t decrease faster than 0.4 mEq/L per hour and more than 10-12 mEq/L per 24 hours!
What is the differential diagnosis of nephrogenic diabetes insipidus?
1) Inherited NDI: due to mutations in the arginine vasopressin receptor gene (AVPR2) or aquaporin gene (AQP2)
2) Acquired NDI: electrolyte disturbances (hypokalemia, hypocalcemia); medications (diuretics, lithium, cisplatin); CKD and tubulointerstitial disease.
3) Syndromic: renal Fanconi, RTA, Bartter syndrome
How does hypokalemia clinically present?
1) Muscle weakness
2) Paralysis (which can cause hypoventilation and apnea)
3) Constipation
4) Ileus
5) Arrythmia (especially ventricular ectopic rhythms and fibrillation)
6) Polyuria
What are the causes of hypokalemia?
1) Fluids and lytes: Diuretics, Laxatives, Metabolic alkalosis
2) GI: diarrhea
3) Endocrine: DKA, primary hyperaldosteronism, Cushing syndrome, adrenal tumour, CAH (rare forms), pituitary tumours producing ACTH)
4) Renal: RTA types I and II, Renal fanconi syndrome, Bartter syndrome, Gitelman syndrome, renal artery stenosis (hyperreninemic state)
Which foods are high in potassium?
Raisins, dates, avocado, beans, squash, tomatoes, lentils, baked potatoes, cocoa, oranges, bananas, french fries, chocolate, carrots
What are the causes of hyperkalemia?
1) Increased potassium intake: IV potassium, oral potassium, transfusion (when renal excretion is impaired 2/2 renal failure or in patients taking ACE inhibitors).
2) Decreased renal excretion: impaired renal function (when the GFR is <15 mL/min per 1.74 m2)
3) Potassium redistribution: metabolic acidosis, insulin deficiency
4) Tissue breakdown: trauma, asphyxia, rhabdomyolysis, chemotherapy (TLS), hemolysis, exercise, hyperkalemic periodic paralysis
5) Medication: beta blockers, potassium sparing diuretics, ACE inhibitors, angiotensin II receptor blockers (ARBs), digoxin, succinylcholine, arginine, NSAIDs, calcineurin inhibitors
6) Pseudohyperkalemia: hemolyzed sampling, severe thrombocytosis, severe polycythemia, leukocytosis
7) Aldosterone deficiency or resistance (pseudohypoaldosteronism): primary adrenal insufficiency, inborn errors of adrenal steroid metabolism
When are calcium infusions indicated for hyperkalemia and how does it work?
If serum potassium level is > 8 mEq/L or there is cardiac dysrhythmia.
It works by increasing the cell’s threshold potential, restoring the voltage difference between these two potentials and decreases the likelihood of dysrhythmia.
What are the key components of hyperkalemia treatment (3)?
1) Stabilize membrane potentials - use ten percent calcium gluconate
2) Promote potassium uptake into cells - can use glucose + insulin and sodium bicarbonate (in setting of acidosis), can also use IV or inhaled albuterol (beta 2 agonist)
3) Enhance the excretion of potassium - can use a cation exchange resin, loop diuretic, dialysis or exchange transfusion (neonates)
What is the differential for an elevated anion gap metabolic acidosis?
MUDPILES.
M = methanol (formic acid and formate)
U = uremia (guanidinosuccinic acid, phosphates, sulfates, other acids)
D = DKA (lactic acid, beta hydroxybutyrate, acetoacetate)
P = paraldehyde, phenformin
I - iron, isoniazid, inborn errors of metabolism
L = lactic acidosis (hypoxia, cardiorespiratory depression, shock, seizures, mitochondrial disease)
E = ethanol, ethylene glycol
S = salicylate
What is the differential for a metabolic alkalosis?
A) saline responsive: urine chloride low, volume depleted.
- vomiting, upper GI suctioning, congenital chloride diarrhea, laxative abuse, diuretics, cystic fibrosis, chloride deficient infant formulas, posthypercapnia syndrome, anion adminsitration (eg phosphate)
b) saline resistant: urine chloride high, volume normal or high.
- RAS, renin secreting tumour, steroids, hypokalemia, steroid hormone synthesis disorder, Liddle syndrome, Bartter syndrome, Gitelman syndrome, primary hyperaldosteronism, licorice
Describe the “paradoxical aciduria” of metabolic alkalosis.
Vomiting and dehydration causes loss of hydrogen ions (acid), sodium, potassium and chloride. RAAS is activated in an effort to increase blood pressure. To increase blood pressure, the kidney increases salt (and water) absorption in the distal nephron. In exchange, the kidney needs to give up other cations (esp hydrogen) to get sodium. Therefore, the urine is acidic.
How does hypocalcemia clinically present?
1) weakness
2) perioral numbness
3) paresthesias
4) carpopedal spasms
5) tetany
6) altered mental status
7) seizures
8) prolonged QT
9) Chvostek sign: tapping parotid gland over facial nerve (in front of ear) causes movement of upper lip.
10) Trousseau sign: carpopedal spasm when BP inflated greater than systolic for 2-5 minutes
How does hypercalcemia clinically present?
1) Bones: pain with osteolytic lesions
2) Stones: urolithiasis, hypertension, polyuria
3) Groans: nausea, vomiting, constipation, weakness
4) Psychiatric overtones: altered mental status
What is the stepwise approach to treating symptomatic hypercalcemia?
1) IV fluids with normal saline to increase urinary excretion +/- diuretic
2) Calcitonin or Bisphosphonates to inhibit bone resorption if present
3) Cinacalcet to activate calcium sensing receptors and decrease release of parathyroid hormone
4) Glucocorticoids to decrease intestinal absorption
In which clinical settings might be suspect hypophosphatemia?
1) Refeeding syndrome in a severely malnourished child
2) Hungry bone syndrome status post parathyroidectomy
3) Hyperparathyroidism (phosphate lost through kidneys)
4) Vitamin D deficiency or rickets
5) Primary renal phosphate wasting
6) Renal Fanconi syndrome
7) GI causes: reduced intake, increased loss (diarrhea), interference with absorption (certain antacids)
What are some laboratory studies that help distinguish prerenal oliguria from acute tubular necrosis?
Apart from volume status (clinical), you can look at:
1) Random urine sodium - prerenal < 20, renal > 20
2) Fractional excretion of sodium - prerenal < 1%, renal >1%
3) Urine osmolality - prerenal > 500, renal < 300
What is the most common cause of AKI in young children in the US?
Acute tubular necrosis 2/2 hypoxia, hypotension or hypovolemia or drug-induced injury.
It used to be caused by hemolytic uremic syndrome (HUS).
List 14 causes of prerenal AKI.
1) Diarrhea
2) Vomiting
3) Osmotic diuresis
4) Diuretics
5) Burns
6) Hemorrhage
7) Septic shock
8) Anaphylaxis
9) Nephrotic syndrome
10) CHD –> heart failure
11) Arrhythmia
12) Cardiomyopathy
13) Tamponade
14) Post cardiac surgery
List 10 causes of renal AKI.
1) Renal venous thrombosis
2) Vasculitis
3) NSAIDs
4) ACE inhibitors
5) Hemolytic uremic syndrome
6) Postinfectious glomerulonephritis
7) Lupus nephritis
8) HSP nephritis
9) IgA nephropathy
10) Crescentic glomerulonephritis
List 6 tubular causes of ATN (renal AKI).
1) Severe prerenal failure
2) Asphyxia/hypoxemia
3) Crystal obstruction
4) Medications
5) Toxins
6) Tumour Lysis Syndrome
List 5 causes of interstitial nephritis.
1) Allergic
2) TINU syndrome
3) Malignancy infiltrate
4) Pyelonephritis
5) Sarcoidosis
List 2 postrenal causes of AKI.
1) Bilateral nephrolithiasis
2) Neoplasm
What is the triad of clinical findings in hemolytic uremic syndrome?
1) Acute renal failure - oliguria, anuria, rare polyuria
2) Acute hemolytic anemia - microangiopathic, fragmented RBCs or schistocytes, DAT negative (nonimmune)
3) Thrombocytopenia
What is the most frequent cause of hemolytic uremic syndrome?
Shiga toxin producing E. coli OH157:H7 serotype. 15% of patients with this infection develop HUS within 2-14 days of diarrhea onset.
Toxin causes endothelial injury with secondary glomerular capillary microthrombi.
(Extra: You can also have genetic causes of atypical HUS, mutations that lead to uncontrolled activation of the complement system when triggered).
What is the prognosis of a child with HUS?
1) 50% require ICU
2) 70% recover completely
3) Approximately 4% die
4) Approximately 15% have long term complications (proteinuria, hypertension, chronic kidney disease)
5) Can develop extra-renal sequelae (colonic strictures, cholelithiasis, diabetes mellitus, brain injury).
In children with HUS, what are the two most important risk factors for poor renal outcome?
1) Anuria for over 10 days
2) Requiring dialysis for more than 3 weeks
How long must a child with HUS be followed as an outpatient?
5 years after the acute episode for all patients.
Indefinitely if there is proteinuria, hypertension or reduced eGFR.
What are the indications for dialysis in the setting of AKI?
Remember AEIOU.
A = acidemia (metabolic acidemia that you can't control with sodium bicarb) E = electrolyte abnormalities (rapid uncontrolled hyperkalemia, symptomatic hyponatremia, hypocalcemia, hyperphosphatemia and hyperuricemia) I = Increased BP (volume dependent HTN or CHF not responsive to diuretics) O = Overload (volume) (needs blood and already overloaded) U = Uremia (acute signs of symptoms of encephalopathy)
What is the definition of AKI versus CKD?
AKI: If it has been less than 3 months and a) the GFR is under 60, b) GFR is decreased by more than 35%, or c) the creatinine increases by over 50%.
CKD: Meets AKI criteria for over 3 months.
What are the GFR criteria for the different stages of Chronic Kidney Disease?
Stage 1: GFR over 90 but abnormal urine or imaging.
Stage 2: GFR 60-89.
Stage 3A: GFR 45-59.
Stage 3B: GFR 30-44.
Stage 4: GFR 15-29.
Stage 5: GFR < 15 or on dialysis.
What are the main causes of CKD in kids that result in kidney transplant?
1) Obstructive uropathy
2) Aplastic, hypoplastic or dysplastic kidneys (CAKUT)
3) Focal segmental glomerulosclerosis (FSGS)
What are four major medications that have improved the lives and outcomes for children living with CKD?
1) erythropoietin - reduces need for transfusions
2) 1,25 dihydroxycholecalciferol - helps prevent and treat osteodystrophy
3) recombinant GH - helps with growth and appetite
4) ACEi or ARB - helps with inhibition of RAAS and to control HTN, slow progression of glomerular fibrosis and ESRD
Explain how you get secondary hyperparathyroidism in CKD mineral and bone disorder.
Decreased GFR leads to decreased excretion of phosphate (ie. hyperphosphatemia) and decreased renal vitamin D production (low active vitamin D). The body doesn’t absorb as much calcium from the GI tract and the bones don’t respond as much to PTH, so there is hypocalcemia. Hypocalcemia causes more PTH to be released and more bone is broken down.
Osteodystrophy begins when the GFR is half the normal rate. It is important to intervene early for prevention and treatment with calcitriol, vitamin D and phosphate binders.
Please list some examples of single-gene ciliopathies with renal involvement.
Von Hippel-Lindau disease Autosomal recessive polycystic kidney disease Nephronopthisis Bardet-Biedl syndrome Retinal-Renal syndrome Senior-Loken syndrome Joubert syndrome Meckel syndrome Alstrom syndrome Sensenbrenner syndrome
What is nephronophthisis?
This is one of the single gene ciliopathies. It is the most common genetic cause of end stage kidney disease in the first 30 years of life.
Recessive mutations in NPHP1 to NPHP11 can cause cysts in the corticomedullary junction to form. Clinical features include anemia, polyuria, polydipsia, isosthenuria, growth failure and progression to ESRD.
What is autosomal dominant polycystic kidney disease and what are the associated genes?
How does ADPKD present and what is the treatment in kids?
Characterized by progressive enlargement of renal cysts, usually bilateral, that occur throughout the nephron. Can get cysts in other organs (liver, seminal vesicles, pancreas, arachnoid). Also associated with intracranial aneurysms, mitral prolapse, diverticulosis and aortic dilatation.
Can present with pain, hematuria, UTI, hypertension and stones. Can be picked up prenatally but usually presents in adulthood.
Diagnose with renal ultrasound. Genetic testing rarely indicated.
Monitor BP + urine, encourage PO water (suppress ADH and slow cyst growth) in kids with family history.
Two genes identified (PKD1, 85%), (PKD2, 15%).
What is autosomal recessive polycystic kidney disease?
What is the clinical spectrum?
What is the associated gene?
Mutations on chromosome 6, PKDHD1 gene cause dilatation of the renal collecting ducts and bilateral renal enlargement with microcysts.
The clinical spectrum includes liver problems such as congenital hepatic fibrosis and Caroli disease (dilation of the intrahepatic bile ducts). Can also have cholangitis, variceal bleeding and hypersplenism.
Many babies die before or at birth. In utero, renal insufficiency can cause oligohydramnios and lung hypoplasia.
How common is nocturnal enuresis and why does it persist in some kids?
At age 5, 20% of kids.
At age 7, 20% of kids.
At age 10, 5% of kids.
At age 15, 1-2% of kids.
Genetic influences are quite strong. If both parents had bed wetting, kid is 75% likely. If one parent, kid if 50% likely. Other thoughts about why it persists include small bladder, delayed neurodevelopment, sleep disorders.
How do we treat nocturnal enuresis? What are the treatment side effects?
Will resolve on its own in 15% of patients.
Can try dry bed training (self waking, cleanliness raining, bladder training, rewards), enuresis alarms.
Medical options include desmopressin (increases distal tubular reabsorption of water and diminishes nighttime bladder volume), or imipramine (increases capacity and decreases detrusor excitability).
Side effects of desmopressin include relapse, nasal irritation, hyponatremia, expensive.
Side effects of imipramine include relapse, drowsiness, agitation, sleep disturbances.
What is pollakiuria?
Excessive daytime urinary frequency (can be up to 50 times per day).
Key features: limited to daytime, occurs after stressful life event.
Self-resolves usually over 6 months. Provide reassurance. No treatment but need to exclude other causes.
What is normal bladder capacity for a child?
Bladder capacity (mL) = [30 + (age in years x 30)]
Can use formula up to age 12, after which the adult value is used which is 390 mL.
How do we define nephrotic syndrome?
1) Proteinuria
2) Hypoalbuminemia
3) Edema
4) Hypercholesterolemia
How is nephritis different than nephrosis?
Nephritis means that there is evidence of glomerular inflammation – on biopsy, there is an increased number of cells within the glomerulus and/or leukocytes. The inflammation disrupts the glomerular membrane structure and function (ie stuff leaks out). Finding of RBC casts is usually diagnostic.
12 year old female with sore throat AND simultaneous cola coloured urine for 2 days. A few days later, she has amber coloured urine, microscopic hematuria, 2+ protein, RBC casts.
What is the most likely cause?
IgA nephropathy
What is IgA nephritis and what are the clinical and histologic features?
Most common type primary glomerular disease. Most common type of glomerulonephritis that causes ESRD (25% will progress).
Variable clinically and histologically. Microscopic hematuria, synpharyngitic hematuria, recurrent hematuria, proteinuria, nephrotic syndrome, nephritic syndrome, acute renal failure.
Glomerular deposits of IgA.
In patients with IgA nephropathy, what are risk factors for developing ESRD? How many go on develop ESRD?
25% develop ESRD over 25 years.
Risk factors = elevated serum creatinine, proteinuria over 1g per day, hypertension, tubular atrophy, interstitial fibrosis severity, extent of glomerular sclerosis.
What are the three major presentations of glomerular involvement?
1) Acute GN: edema, proteinuria of 1+ or more, hypertension, oliguria, dysmorphic RBCs or casts on urinalysis
2) Chronic GN: minimal acute symptoms; fatigue, FTT, anemia, hypertension, abnormal urinalysis, azotemia, metabolic acidosis, hypocalcemia, hyperphosphatemia
3) Nephrotic syndrome: proteinuria of over 40 mg/square metre per hour, edema, hypoalbuminemia and hypercholesterolemia
What tests do you order for glomerulonephritis?
First line: urine dipstick, urine microscopy; serum electrolytes, BUN, Cr; serum C3 and C4; ASOT, throat culture, skin culture (if impetigo), serum albumin
Second line: ANA, anti DNA (if suspecting lupus), Hep B and C serology; ANCA (if rapidly progressive GN or vasculitis)
Which glomerular diseases have an underlying genetic cause?
1) Congenital nephrotic syndrome - recessive, NPHS1
2) Diffuse mesangial sclerosis - recessive, WT1
3) Denys-Drash syndrome - recessive, WT1
4) Frazier syndrome - recessive, KTS
5) FSGS - dominant or recessive; NPHS2, TRPC6, ACTN4, INF2, PLCE1
6) Alport syndrome - X linked r/d; COL4A5
7) Nail-patella syndrome - dominant, LMX1B
8) Steroid resistant NS with sensorineural deafness - dominant, COQ6
9) C3 Glomerulopathy - recessive; Factor H, CFHR
When you have hypocomplementemia, which types of GN do you consider?
1) Postinfectious GN (acute post strep)
2) Lupus nephritis
3) Immune complex membranoproliferative glomerulonephritis
4) C3 glomerulopathy
5) Atypical HUS
Does treating streptococcal skin or pharyngeal infections prevent acute post streptococcal glomerulonephritis?
No.
It decreases spread to other kids from the index case, however.
What is the usual time course of acute post streptococcal glomerulonephritis?
Symptoms start about 1-2 weeks after. It can be up to 6 weeks after a pyoderma.
Acute phase includes HTN, gross hematuria, oliguria, edema and tea coloured urine) and can last up to 3 weeks.
Serum C3 may be low for up to 8 weeks.
Chronic microscopic hematuria can last for up to 2 years.
Name that diagnosis: recurrent gross hematuria and persistently low C3, normal C4. What are the next steps for evaluation? What is the prognosis?
C3 glomerulopathy, including dense deposit disease and C3 glomerulonephritis.
Evaluation includes genetic testing for alternative complement regulatory genes, checking for C3 nephritic factor and kidney biopsy.
May lead to ESRD in ten years in 50% of patients.
How common is hematuria in children?
Microscopic hematuria occurs in 0.5-2% of school age kids, often transient. No cause found in 70-80% of cases.
What is the top cause of microscopic hematuria?
Hypercalciuria (>4 mg/kg per day)
How to you distinguish upper versus lower tract GU bleeding?
Lower tract - bright red blood, clots.
Upper tract - brown, tea/cola coloured.
Glomerular - casts, small and dysmorphic RBCs.
10 Y M with BRB at the end of micturition. What is the most likely diagnosis?
Urethroragia.
Due to engorged vessels around the entry of the prostatic duct into the urethra. Benign condition associated with hormonal changes at adolescents. Resolves spontaneously in weeks to months.
What is blue diaper syndrome and how is it different from pink diaper syndrome?
Blue = bad.
Rare, autosomal recessive inborn error of amino acid metabolism. Due to defects in intestinal absorption of tryptophan. You get increased degradation of tryptophan by bacteria, more production and absorption of indican (a breakdown product). When they pee, they pee out indican (indicanuria). Exposure of this to air oxidizes the pee to an indigo blue colour. Can be associated with visual problems, hypercalcemia and nephrocalcinosis.
Pink diaper syndrome is benign. Red brown spotting caused by normal urate crystals which turn pink on exposure to air, forming a powder that can be scraped from the diaper.
What is the initial work up for coffee or cola coloured urine?
Do a urinalysis, r+m. If proteinuria and RBC casts, think GN.
For GN, order serum BUN, Cr, electrolytes. Sent ASOT, C3, C4.
If vasculitis, send ANCAs. If lupus, check ANA and antiDNA. If Alport on FHx, obtain hearing test.
What is the initial workup if there is bright red, painless hematuria?
Renal US to rule out malignancy, calculi, trauma, large cyst, PCKD, HN.
If suspecting SCD, obtain Hb electrophoresis.
What is the initial workup of bright red hematuria with dysuria?
1) Renal US to rule out calculi
2) Calcium to creatinine ratio to rule out hypercalciuria.
3) Urine culture to rule out UTI.
What is on the differential if the dipstick is positive for blood but microscopy is negative for RBCs?
Dyes from beets or candy, hemoglobinuria (hemolysis), myoglobinuria (rhabdomyolysis).
How do we define hypertension in children 1 -12 years old?
Normal BP: <90th percentile
Elevated BP: 90-95th percentile
Stage 1 HTN: over 95th to 95th percentile + 12
Stage 2 HTN: over 95th percentile + 12
How do we define hypertension in children over 13 years?
Like adults. Normal BP: <120/<80 Elevated BP: 120-129/<80 Stage 1 HTN: 130-139/80-89 Stage 2 HTN: 140/90 or above
What are some common causes of artifactual blood pressure elevation?
BP cuff too small Arm below level of heart Child is talking Feet off the ground Child given no time to relax
What are some common causes of artifactual low blood pressure?
Arm is above the level of the heart
How much can we expect the blood pressure to fall between visits after white coat hypertension?
15/7 by the third visit.
Note: If stage 2 at the first visit, then they need immediate evaluation off the bat.
How do you determine the optimum cuff size for obtaining a blood pressure?
Inflatable bladder length encircles at least 80% of the arm. Height of the cuff should be the largest size that fits comfortably from axilla to elbow.
How is hypertension defined in the neonate and when should it be treated?
Term neonate >90/60
Preterm neonate >80/45
Treat if sustained systolic >100
What are the indications for pharmacologic treatment of HTN in children and adolescents?
1) Symptomatic HTN
2) Stage 2 HTN
3) Stage 1 HTN not responding to 4-6 mos of the non-pharmacologic therapy
4) Secondary HTN
5) Organ damage (eg LVH on Echo)
6) Type 1 and 2 Diabetes with BP >90th percentile
What are some risk factors for HTN in children? List 7.
1) Family history (1 parent HTN = 25%, 2 parent HTN = 45%)
2) Genetic factors
3) Obesity
4) History of renal disease
5) Diet
6) Low birth weight
7) Additional cardiovascular risk factors: tobacco, diet, serum lipids, lack of exercise
List five causes of secondary hypertension.
1) UTI
2) Vasculitis
3) Renal artery stenosis
4) Drug-induced (sympathomimetics, steroids, NSAIDS, OCPs, illicit drugs)
5) Adrenal disorder - hyperaldosteronism
6) Pheochromocytoma
7) Hyperthyroidism
8) Coarctation of the Aorta
9) OSA
10) CKD
11) Arteritis
12) Renal malformation, renal tumour
13) Lupus nephritis
14) Collagen vascular disease
What is orthostatic proteinuria?
Usually in adolescents.
Benign condition where there are normal rates of protein excretion when recumbent but have increased excretion rates when upright/ambulant.
Confirm this with first morning urine specimen with a PCR < 0.25.
What level constitutes significant proteinuria?
Protein excretion of >4 mg/metre squared/hour on a timed urine collection. Nephrotic range is >40.
Urine CPR >0.5 in children under 2 years and >0.2 in children over 2 years is abnormal.
At what serum albumin concentration does edema start to develop?
When serum albumin is less than 2.5 g/dL.
What is the most common cause of nephrotic syndrome in children?
Minimal change nephrotic syndrome.
Etiology unknown, thought to do with abnormal T cell function. Definitive way to prove it is with renal biopsy, but age at presentation is often indicative (ie. over age 1 year and under age 8).
What are the clinical features, worrisome complications and typical treatment response of children with minimal change nephrotic syndrome?
1) Edema, normal or slightly increased BP, No gross hematuria. 1/3 will have microscopic hematuria without RBC casts. Normal BUN, Cr, Electrolytes. Low serum calcium and albumin.
2) Watch out for hypercoagulable state/thrombosis and peritonitis. (strep pneumo or Ecoli).
2) 90% of kids respond to daily prednisone within the first month of treatment and have SSNS (steroid sensitive NS). If prolonged for another month, another 4% will respond. Despite 2 months of therapy, 3% will be steroid resistant (SRNS). If SRNS, consider kidney biopsy and treatment with cyclophosphamide or tacrolimus.
What are the indications for Lasix and Albumin in Nephrotic Syndrome and what are the doses of each when you administer it?
1) Severe edema with anasarca, cellulitis or skin breakdown
2) Respiratory decompensation from pleural effusions
Infuse 25% albumin solution at 0.5 - 1 g/kg of albumin over 1-2 hours THEN furosemide 1-2 mg/kg.
A 5 year old child presents with puffy eyes and lab features of nephrotic syndrome. He does not respond to steroids after 6 weeks. What is the most likely diagnosis and prognosis?
Focal segmental glomerulosclerosis (FSGS), 20% of cases of pediatric nephrotic syndrome. Very often genetic 2/2 mutations in podocytes. Can be AR (podocin) or AD (ACTN4).
Can progress to ESRD. Might benefit from ACE inhibitors. Don’t respond to steroids.
Which kind of urinary crystals are always pathologic?
Cystine. Indicates cystinuria, amino acid transport defect where the dibasic amino acids (cystine, orthinine, arginine and lysine) are affected. Remember mnemonic COAL.
You get cystine crystals and nephrolithiasis.
What is the most common cause of urinary tract obstruction in the newborn?
Posterior urethral valves, persistent urogenital membranes only in boys. You often get high pressures and reflux, damaging the renal parenchyma. Can progress to ESRD.
What is the most common renal abnormality detected on antenatal ultrasound?
Hydronephrosis.
Incidence 0.5-1%.
Cutoff is renal pelvic diameter of over 5 mm then grades 0-IV based on degree of dilation, number of calyces observed and evidence of any atrophy.
Repeat US advised at 48-72 hours after birth and then again at 4-6 weeks after birth. After that, might need VCUG and urology referral.
List a differential diagnosis for pathologic causes of prenatal hydronephrosis?
1) Ureteropelvic junction obstruction
2) Posterior urethral valves
3) VUR
4) Ectopic ureter
5) Ureterocele
6) Megaureter
7) Urethral atresia in prune belly syndrome
What are signs and symptoms common in all types of renal tubular acidosis?
Growth failure, polyuria, polydipsia, recurrent dehydration, vomiting.
Hyperchloremic metabolic acidosis, normal serum anion gap.
What is the defect in Type 1 (distal) RTA?
Inability of the distal tubule to secrete hydrogen.
K normal or low
Frequent nephrocalcinosis
Urine pH >5.5
What is the defect in Type 2 (Proximal) RTA?
Decreased ability of the proximal tubule to reabsorb filtered bicarb.
K normal or low
Rare nephrocalcinosis
Urine pH <5.5
What is the defect in Type 4 RTA?
Acquired or inherited tubular insensitivity to aldosterone or to an absence of aldosterone.
K high
Rare nephrocalcinosis
Urine pH <5.5
What is the urine anion gap and how is it clinically useful in nephrology?
Urinary anion gap = (Urine) Sodium + Potassium - Chloride.
Screening test for RTA, esp distal. Indirect estimate of urinary ammonium excretion (urine acid excretion).
If negative, suggests large chloride excretion in urine and adequate acid excretion. It is negative in hyperchloremic MA due to diarrhea, untreated proximal RTA and prior administration of acid. If positive, suggests acidification defect like distal RTA. If you have a positive result, you should look at urine pH and plasma potassium. If urine pH is >5.5 and K is low-normal, distal RTA. If urine pH < 5.5 and high K, type 4 RTA.
Results not reliable if large amounts of unmeasured anions like ketoacids, penicillin, salicylates.
How to you treat renal tubular acidosis?
Alkali therapy using sodium citrate or sodium bicarbonate, with the goal of a normal plasma bicarbonate level.
Patients with distal RTA only require 2-3 mEq/kg/day.
Patients with proximal RTA require large quantities, 5-20 mEq/kg/day.
For Type 4 RTA, usually need low dose alkali therapy, 1-3 mEq/kg/day plus a potassium restricted diet +/- mineralocorticoid therapy (if hypoaldosteronism).
What is renal Fanconi syndrome?
Manifestation of multiple disorders that cause abnormal transport within the proximal tubule and you get abnormal excretion of glucose, phosphate, potassium, amino acids, bicarbonate. Cystinosis (lysosomal storage disease causing abnormal accumulation of cystine) is most common cause. Also consider galactosemia, tyrosinemia, fructose intolerance.
Metabolic bone disease 2/2 phosphaturia and hypophosphatemia.
Metabolic acidosis 2/2 bicarbonate loss.
What is renal glucosuria?
Benign condition, commonly familial, usually due to genetic abnormalities in renal glucose reabsorption. Mild glucosuria is typical.
Need to make sure that there are no other symptoms, hypokalemia, MA or elevated serum creatinine.
What is the etiology and clinical presentation of acute interstitial nephritis (AIN)?
It is caused by an immune mediated inflammatory response. Involves the renal interstitium and tubules, usually spares the glomeruli and vasculature.
Certain medications can cause it such as antibiotics (penicillin analogs, cephalosporins, sulfonamides, rifampin); NSAIDS, diuretics, PPIs.
Can present in a spectrum - can get acute renal failure, isolated tubular disorders etc. Might get polyuria and polydipsia as well as hypersensitivity signs including fever, rash, arthralgias.
Lab abnormalities depend on which area is affected. Proximal tubule = glucosuria, bicaronaturia, phosphaturia, aminoaciduria. Distal = hyperkalemia, sodium wasting. Medullary = sodium wasting, urinary concentrating defects.
The risk is (BLANK) times more for UTI in uncircumcised vs circumcised male infants?
10x
What can cause a falsely low colony count despite a culture positive UTI?
1) High urine volume
2) Recent antibiotics
3) Slow growing organisms (enterococcus, staph saprophyticus)
4) low urine pH and low specific gravity
5) ureter obstruction
6) chronic or indolent infection
7) inappropriate culture technique
What pathogens are associated with UTIs in children?
E.coli is 80-90% of initial UTIs.
Other organisms: Klebsiella pneumoniae, Enterobacter, Pseudomonas, Proteus Miribalis, some Staphylococcus species.
How do you differentiate cystitis versus pyelonephritis?
Pyelonephritis has more constitutional symptoms
