Medical brain notes 15

  CONGENITAL ANOMALIES OF THE KIDNEY Renal agenesis ·              Bilateral agenesis  is incompatible with life. Ultrasound shows oligohydramnios.   ·              Affected fetuses typically also have Potter facies (flattened nose, posteriorly rotated ears, and recessed chin); talipes equinovarus (talus [ankle]+ pes [foot] and equino [heel] + varus [turned upward] = clubfoot); and pulmonary hypo-plasia.   ·              In  unilateral agenesis , the remaining kidney undergoes compensatory hyper-trophy. Patients often have adequate renal function and are asymptomatic.   Hypoplasia  is failure of a kidney (usually unilateral) to develop to normal weight;the hypoplastic kidney has a decreased number of calyces and lobes. Horseshoe kidney  is a common congenital anomaly tha...

  CYSTIC DISEASE Autosomal recessive polycystic kidney disease  (also called infantile polycystic kid-ney disease or renal dysgenesis Potter type I) is a rare autosomal recessive disease that presents in infancy with progressive and often fatal renal failure. A mutation in the  PKHD1  gene is implicated. The kidneys are bilaterally enlarged and have a spongelike cut surface. The liver may have multiple hepatic cysts and cirrhosis may develop in childhood. Pulmonary hypoplasia is present to varying degrees Autosomal dominant polycystic kidney disease  (also called adult polycystic kidney   disease or renal dysgenesis Potter type III) is an autosomal dominant disease that affects 1 in 1,000. There is most frequently a mutation of the  PKD1  gene on chro-mosome 16 which produces a transmembrane protein called polycystin 1. Other mutations involve  PKD2  and polycystin 2. Clinically, patients are asymptomatic with normal renal function until...

  GLOMERULAR DISEASES   Immune mechanisms play a role in the pathogenesis of most glomerular diseases, either via deposition of immune complexes or injury from antibodies. Glomerular diseases may be divided into those originating in the kidney and those caused by systemic disease (secondary).   Glomerular disease may present clinically as  nephrotic  or  nephritic syndrome .Their clinical features are different. Renal biopsy can yield a definitive diagnosis when light microscopy features are considered in concert with immunofluoresence (IF) and electron microscopy (EM).  

  PRIMARY GLOMERULOPATHIES (NEPHRITIC SYNDROME)   Acute poststreptococcal glomerulonephritis (APSGN)  (or acute proliferative glomer-ulonephritis or postinfectious glomerulonephritis) is an immune complex disease that typically occurs 2–4 weeks after a streptococcal infection of the throat or skin. There is a decreasing incidence in the United States; children are affected more often than adults.   The infecting organism is most commonly β -hemolytic group A  streptococci , but APSGN can also be caused by other bacteria, viruses, parasites, and even systemic diseases (SLE and polyarteritis nodosa). Clinically, it presents with nephritic syn-drome with elevated antistreptolysin O (ASO) titers (when related to streptococcal infection) and low C3.   Renal biopsy.  Light microscopy shows an infiltrate of neutrophils in the glomeruli;   the process is diffuse, that is, it involves all the glomeruli. Immunofluorescence shows granular deposits of IgG and...

  PRIMARY GLOMERULOPATHIES (NEPHROTIC)   Membranous glomerulonephritis  is a common cause of nephrotic syndrome in   adults that is mediated by immune complexes.   Most cases (85%) are idiopathic; in most of these cases, autoantibodies cross-react with podocyte antigens. Membranous glomerulonephritis may also be caused by drugs (penicillamine), infections (hepatitis virus B and C, syphilis, etc.), and systemic diseases (SLE, diabetes mellitus, etc.). It has also been associated with malignant car-cinomas of the lung and colon, and there may be a genetic predisposition.   Renal biopsy shows diffuse thickening of the capillary walls. Basement membrane projections (“spikes”) are seen on silver stains. Immunofluorescence shows a gran-ular and linear pattern of IgG and C3. Electron microscopy shows subepithelial deposits along the basement membranes with effacement of podocyte foot processes.   The clinical course is variable and may lead to spontaneous rem...

  SECONDARY GLOMERULONEPHRITIS Secondary glomerulonephritis  is glomerular disease that is secondary to other dis-ease processes. Diabetes  causes nodular glomerulosclerosis, hyaline arteriolosclerosis, and diabetic   microangiopathy. Clinically, diabetic patients may develop microalbuminuria that can progress to nephrotic syndrome. Systemic lupus erythematosus  can cause various patterns of damage to the kidney   with clinical features that can include hematuria, nephritic syndrome, nephrotic syndrome, hypertension, and renal failure.

  CHRONIC GLOMERULONEPHRITIS End-stage renal disease  is the final stage of many forms of glomerular disease. It is   characterized by progressive renal failure, uremia, and ultimately death. Clinical features include anemia, anorexia, malaise, proteinuria, hypertension, and azotemia. Urinalysis shows broad, waxy casts. On pathologic examination, the kidneys are grossly small and shrunken; microscopic exam shows hyalinization of glomeruli, interstitial fibrosis, atrophy of tubules, and a lymphocytic infiltrate. Treatment is dialysis and renal transplantation.

  TUBULOINTERSTITIAL NEPHRITIS Tubulointerstitial nephritis  is an acute or chronic inflammation of tubules and   interstitium. It can be due to many causes, including medications, infections, acute pyelonephritis, systemic lupus erythematosus, lead poisoning, urate nephropathy, or multiple myeloma. •           Acute pyelonephritis  refers to bacterial infections involving the renal pelvis,   tubules, and interstitium. Pyelonephritis affects females much more than males, but the incidence increases in older males with prostatic hyperplasia.   Ascending infection is the most common route of infection. Causative organ-isms include gram-negative enteric bacilli,  Escherichia coli, Proteus, Klebsiella,  and  Enterobacter . Predisposing factors include urinary obstruction, vesicoure-teral reflux, pregnancy, urethral instrumentation, diabetes mellitus, benign prostatic hyperplasia, and other renal pathol...

  ACUTE TUBULAR INJURY   Acute tubular injury  (ATI) is acute renal failure associated with potentially revers-ible injury to the tubular epithelium. It is the most common cause of acute renal failure in the United States. It is characterized by oliguria with elevation of blood urea nitrogen (BUN) and creatinine; metabolic acidosis and hyperkalemia; and dirty brown granular casts and epithelial casts on urinalysis.   •           Ischemic acute tubular necrosis  is the most common cause of ATI. The condi-tion is due to decreased blood flow caused by severe hemorrhage, severe renal vasoconstriction, hypotension, dehydration, or shock.   •           Nephrotoxic ATN  has a large number of causes, including drugs (e.g., poly-myxin, methicillin, gentamicin, sulfonamides); radiographic contrast agents; heavy metals (e.g., mercury, lead, gold); organic solvents (e.g., car...

  UROLITHIASIS   Renal calculi  occur in up to 6% of the population; men are affected more often than   women.   •           Stone composition.  Most (75%) stones are calcium oxalate stones. Magne-sium ammonium phosphate (“struvite”) stones are associated with infection by urea-splitting bacteria (proteus), and these stones often form large staghorn calculi. Uric acid stones are seen in gout, leukemia, and in patients with acidic urine. Cystine stones are uncommon. •           Pathology.  Most stones are unilateral stones that are formed in the calyx,   pelvis, and urinary bladder.   •           Clinical features.  Calcium stones are radiopaque and can be seen on x-ray.   Renal colic may occur if small stones pass into the ureters. Stones may cause hematuria, urinary obstruction, and predispose to in...