6. Nephrology Flashcards
Definition of acute kidney injury ?
- A rapid decline in renal function, with an increase in serum creatinine level (a relative increase of 50% or an absolute increase of 0.5 to 1.0 mg/dL)
Acute renal failure (ARF) ?
The creatinine may be normal despite a markedly reduced glomerular filtration rate (GFR) in the early stages of acute kidney injury (AKI) due to the time it takes for creatinine to accumulate in the body.
RIFLE criteria ?
- Classification severity of acute kidney injury.
- RISK:
- 1.5x increase in Cr.
- GFR decreased by 25%.
- Urine output: <0.5 mL/kg?hr for 6 hrs. - INJURY:
- 2x increase in Cr.
- GFR decreased by 50%.
- Urine output: <0.5 mL/kg/hr for 12 hrs. - FAILURE:
- 3x increase in Cr.
- GFR decreased by 75%.
- Urine output: <0.5 mL/kg/hr for 24 hrs. or anuria for 12 hrs. - LOSS:
- Complete loss of kidney function (i.e. requiring dialysis) for more than 4 wks. - ESRD:
- Complete loss of kidney function (i.e. requiring dialysis) for more than 3 months.
- Svereity (stage 1-3).
- Outcome (4 and 5)
The most common cause of death in AKI ?
Infections (75%).
Types of AKI ?
- Prerenal AKI (decrease in renal blood flow 60% of cases)
- Intrinsic AKI. (40%)
- Psotrenal AKI. (5%)
Prerenal AKI causes ?
- Most common cause of AKI; potentially reversible.
- Hypovolemia (dehydration, excessive diuretic use, vomiting, diarrhea, burns, hemorrhage)
- CHF. (less blood will be send to the tissues)
- Hypotension.
- Renal arterial obstruction.
Diagnostic Approach in AKI ?
- hx and PE.
- To determine the duration of renal failure. A baseline Cr level provides this info.
- To determine whether AKI is due to prerenal, intrarenal, or postrenal.
- Medication review.
- Urinalysis.
- Urine chemistry (FENa, osmmolality, urine Na+, urine Cr)
- Renal US ( to rule out obstruction)
How to know whether AKI is due to prerenal, intrarenal, or postrenal ?
- This is done via combination of H&P and labs findings:
- Signs of volume depletion and CHF suggest a prerenal etiology.
- Signs of an allergic reaction (rash) suggest acute interstitial nephritis (an intrinsic renal etiology).
- A suprapubic mass, BPH, or bladder dysfunction suggests a postrenal etiology.
Medication causes Intrarenal AKI ?
- Acute tubular necrosis ->
- Aminoglycosides.
- Heavy metals (leads).
- Myoglobin (damaged muscle).
- Ethylene glycol. (anti-freeze)
- Uric acid
- Radiocontrast dye. - Acute Interstitial AKI -> (type I and IV hypersensitivity)
- NSAIDs.
- Penicillin.
- Diuretics.
Prerenal AKI ?
- Urinalysis:
- BUN/Cr ratio:
- FENa:
- Urine osmolality:
- Urine sodium:
- Urinalysis: hyaline cast
- BUN/Cr ratio: >20:1
- FENa: <1%
- Urine osmolality: >500 mOsm
- Urine sodium: <20
Intrinsic AKI ?
- Urinalysis:
- BUN/Cr ratio:
- FENa:
- Urine osmolality:
- Urine sodium:
- Urinalysis: abnormal.
- BUN/Cr ratio: <20:1
- FENa: >2-3%
- Urine osmolality: 250-300 mOsm.
- Urine sodium: >40
Acute tubular necrosis urine sediment findings ?
- Full brownish pigment, granular casts with epithelial cells.
Intrinsic AKI causes ?
- Tubular diseases (ATN): can be caused by ischemia (most common), nephrotoxins.
- Glomerular disease (acute glomerulonerphritis): for example, Goodpasture syndrome, Wegener granulomatosis, poststreptococcal GN, lupus.
- Vascular disease: for example, renal artery occulsion, TTP, HUS.
- Interstitial disease. (allergic interstitial nephritis, often due to hypersensitivity reaction to medication)
The 3 basic tests for postrenal failure ?
- PE: palpate the bladder.
- US: look for obstruction, hydronephrosis.
- Catheter: look for large volume of urine.
Postrenal AKI causes ?
- Urethral obstruction. (2ndary to enlarged prostate (BPH) is the most common cause).
- Obstruction of solitary kidney.
- Nephrolithiasis.
- Obstructing neaplasms (bladder, cervix, prostate, and so on)
RBC casts in ureine sediment indicates ?
Glomerular disease.
WBC casts in ureine sediment indicates ?
Renal parenchymal inflammation “ acute interstitial nephritis “
Fatty casts in ureine sediment indicates ?
Nephrotic syndrome
What are the nosy common mortal complications in early phase of AKI ?
- Hyperkalemic cardiac arrest.
- Pulmonary edema.
Chronic Kidney Disease is ?
Defined as either:
- Decreased kidney function (GFR<60 mL/min)
OR
- Kidney damage (structural or functional abnormalities).
for at least 3 months.
Causes of Chronic Kidney Diseases ?
- Diabetes. (most common 30%).
- HTN (25%)
- Chronic GN.
- Interstitial nephritis, PCKD.
- any cause of AKI may lead to CKD if prolonged and/or treatment is delayed.
NUTRITIONAL THERAPY in Chronic kidney diseases ?
- WATER RESTRICTION
- intake depends on daily urine output.
- SODIUM RESTRICTION:
- depends on the degree of hypertension and edema
- salt substitutes should not be used because they contain KCl
life-threatening complications in CKD ?
- Hyperkalemia: check ECG (although it K can be high without ecg changes)
- Pulmonary edema (2ndary to volume overload) (look for recent weight gain).
- Infections
Absolute Indications for Dialysis ?
- Acidosis: significant, intractable metabolic acidosis.
- Electrolytes: severe, persistent hyperkalemia.
- Intoxications: methanol, ethylene glycol, lithium, aspirin.
- Overload: hypervolemia not managed by other means.
- Uremia (severe): based on clinical presentation NOT labs values.
Symptoms of uremia ?
- Nausea and vomiting.
- Lethargy/detrioration in mental status, encephalopathy, seizures.
- Pericarditis.
Dialyzable Substances ?
- Salicylic acid.
- Lithium.
- Ethylene glycol.
- Magnesium-containing laxatives.
Complications of Hemodialysis during dialysis ?
- Hypotension. “most frequent”
- Arrhythmias.
- Exsanguination.
- Seizures.
- Fever.
Complications of Hemodialysis between treatments ?
- Hyper/Hypotension.
- Edema.
- Pulmonary edema.
- Hyperkalemia.
- Bleeding,
- Clotting access.
Long term Complications of Hemodialysis ?
- Hyperparathyroidism.
- CHF.
- AV access failure.
- Pulmonary edema.
- Neuropathy.
- Anemia.
- GI bleeding.
Kt/V ?
- Kt/V is the preferred method for measuring the dialysis
dose. - Kt/V is defined as the dialyzer clearance of urea (K) multiplied by the duration of the dialysis treatment (t, in minutes) divided by the volume of distribution of urea in the body (V, in mL), which is approximately equal to the total body water, corrected for volume lost during ultrafiltration .
Absolute contraindications of Peritoneal Dialysis ?
- Peritoneal fibrosis and adhesion following intraabdominal operation.
- Inflammatory gut diseases.
AZOTEMIA def ?
A pathologic increase in urea and other nitrogenous substances in the blood.
UREMIA def ?
Systemic manifestation of severe persistent decrease in renal function.
AKIN Criteria?
- for diagnosing AKI.
- Time course – rapid (<48hours).
- Reduction in Kidney function
- increase serum creatinine (absolute increase of >0.3mg/dl or percentage increase of > 50%)
- decrease urine output (<0.5ml/kg/hr for> 6hours)
RIFLE Criteria: URINE OUTPUT ?
- ANURIA: <100 mL/24 h
- OLIGURIA: 100-400 mL/24h
- NONOLIGURIA: : > 400 mL/24h
- 50-60% of AKI cases are nonoliguric
Treatment of Potassium >6.0 mmol/L ?
– calcium resonium 15g QDS PO
– If septic or rising quickly treat as though K+ 6.5
Treatment of Potassium >6.5 mmol/L ?
– dextrose-insulin (50ml 50% Dextrose with 10units Actrapid insulin, IV over 5mins) Monitor BM
– calcium resonium 15g QDS PO.
Treatment of Potassium >7 mmol/L ?
– Calcium gluconate. – Dextrose insulin. – Nebulised salbutamol 5mg – IV sodium bicarbonate. – Calcium resonium.
Treatment approach to hyperkalemic emergencies ?
including MOA?
- Antagonism of membrane actions of potassium:
- Calcium.
- Drive extracellular potassium into the cells:
- Insulin and glucose.
- Sodium bicarbonate. (if metabolic acidosis)
- B-2-adrenergic agonists. (salbutamol)
- Removal of potassium from the body:
- Loop or thiazide diuretics.
- Cation exchange resin.
- Dialysis. preferably if severe.
HYPERKALEMIA ?
- Normal Potassium range is 3.5 - 5mmol/L.
- Signs and symptoms: muscle weakness and arrhythmia (VF).
- ECG changes:
– Flattened P waves
– Broad QRS complex
– Slurring of ST segment
– Tall tented T waves
HTN management in CKD ?
- Diuretics
- Ca channel blockers.
- ACEI, ARB.
ANEMIA treatment in CKD ?
- ERYTHROPOETHIN:
- increases Hb and HT levels in 2-3 weeks.
- side effect: hypertension (so its CI if we have HTN patient).
- Iron supplements:
- in case of low plasma ferritin (<100 ng/mL).
- Folic acid supplements:
- removed by dialysis.
- necessary for RBC formation.
- Levels should be:
1. Hg: 11-12 g/dl.
2. Ht: 33-36%.
Management of RENAL OSTEODYSTROPHY in CKD ?
– dietary phosphorus restriction (<1000 mg/day),
– oral P-binding agents (limit P absorption from bowel, with each meal) (e.g. calcium carbonate)
– vit. D
– increase sensitivity of Ca receptors in parathyroid glands (sensipar)
– subtotal parathyroidectomy,
– calcitriol
Proteinuria is?
- Defined as the urinary excretion of >150mg protein/24 hrs.
Proteinuria classifications ?
A. Glomerular.
B. Tubular.
C. Overflow proteinuria.
D. Other causes of proteinuria (UTI, fever, heavy exertion/stress,CHF..etc)
Nephrotic syndrome ?
- Proteinuria “ >3.5 mg/24 hr”
- Hypoalbuminemia.
- Hyperlipidemia .
- Edema. “often initial complaint”.
- Lipiduria.
Causes of Nephrotic syndrome ?
- Primary glomerular disease. (50-75%):
1. Membranous nephropathy (most common in adults 40%).
2. Focal segmental glomerulosclerosis (FCGS) (35%).
3. membranoproliferative GN (15%).
4. Minimal change disease (MCD) commonest in kids 75%. - Systemic disease: diabetes, collagen vascular disease, SLE, RA, HSP, PAN, Wegener granulomatosis.
- Amyloidosis, cryglobulinemia.
- Drugs/toxins.
- Infections.
- Multiple myeloma.
Pathology of Membranous nephropathy or “MEMBRANOUS
GLOMERULONEPHRITIS” ?
-Inflammation of glomerular basement membrane triggered by immune complex deposits -> increased permeability, proteinuria -> nephrotic syndrome.
Pathology of Focal segmental glomerulosclerosis (FCGS) ?
▪ Histologic finding of glomerular damage, not distinct disease.
▪ Affects parts (segmental) of some (focal) glomeruli of nephron; damage, scarring → proteinuria
▪ Foot processes of podocytes damaged → plasma proteins, lipids permeate glomerular filter
▪ Proteins, lipids trapped → build up inside glomeruli → hyalinosis (hyaline/ glassy view on histology) → scar tissue (glomerulosclerosis)
Causes of Focal segmental glomerulosclerosis (FCGS) ?
▪ Primary: unknown
▪ Secondary: result of underlying cause
- Sickle cell disease, HIV, renal hyperfiltration (e.g. unilateral renal agenesis), heroin abuse
▪ Genetic forms: FSGS 1–6
Hematuria ?
- Defined as >3 erythrocytes/HPF on urinalysis.
- Consider gross painless hematouria to be a sign of bladder or kidney cancer until proven otherwise.
Nephritic syndrome ?
- Hematouria.
- Oliguria.
- Azotemia.
- HTN.
- Edema.
Pathology of Minimal change disease ?
▪ Type of glomerulonephritis; podocytes in glomeruli damaged by T cells cytokines
▪ Foot processes of podocytes damaged, flattened (AKA effacement) → lose function as barrier → albumin permeates, bigger proteins cannot get through (selective proteinuria)
MEMBRANOUS GN findings on sliver staining ?
“SPIKES” ON THE OUTER ASPECT OF GBM.
IDIOPATHIC MEMBRANOUS NEPHROPATHY ?
Ag: phospholipase A2receptor (PLA2R) (may be shown in a biopsy)
in patient;’s blood: anti PLA2R
THE ACUTE NEPHROTIC SYNDROME info about pathology ?
The structural abnormality shared by all nephrotic conditions or diseases with heavy proteinuria is diffuse simplification or “fusion” of the foot processes of the glomerular visceral epithelial cells.
THE ACUTE NEPHRITIC SYNDROME info about pathology ?
Diseases characterized by the acute nephritic syndrome are associated invariably with deposition of immune complexes in the more proximal layers of the glomerular capillary wall, in close proximity to the endothelial cell surfaces
Diffuse proliferative glomerulonephritis in a patient with recent hepatitis C infection ?
- Ultrastructural details of subendothelial deposits.
- Immune deposits are present exclusively in the subendothelial space.
- Early formation of a second basement membrane (arrows) by the displaced endothelium has resulted in an early double contour.
CONDITIONS ASSOCIATED WITH DIFFUSE PROLIFERATIVE GLOMERULONEPHRITIS ?
- Acute Postinfectious Glomerulonephritis:.
- Diffuse proliferative lupus nephritis.
- Dense Deposit Diseases early phase.
- Essential mixed cryoglobulinemia, early phase
Clinical manifestation of Membranoproliferative glomerulonephritis ?
and PATTERN OF INJURY ?
CHRONIC nephrotic syndrome and nephritic syndrome
- IMMUNE DEPOSITS-MEDIATED DISEASES (glomerulonephritis)
- THROMBOTIC ANGIOPATHIES
- DEPOSITION DISEASE