Acute vs. Chronic Renal Failure

Acute renal failure (ARF): caused by dehydration, blood loss from major surgery or injury, or the use of medications, such as contrast agents used in X-ray tests, antibiotics such as gentamicin, or nonsteroidal anti-inflammatory drugs (NSAIDS) such as aspirin or ibuprofen.
Chronic kidney disease (CKD): caused by a long-term disease, such as high blood pressure or diabetes, that slowly damages the kidneys and reduces their function over time.

ARF usually presents with decrease urine output and electrolyte abnormalities and sudden elevation of BUN and Cr (BUN more)

CRF usually presents with mild elevation of Cr over a long time and sx's don't present until only 10%-20% kidney function is left. On U/S CRF shows more atrophic kidney

Correcting anion gap for albumin

observed anion gap =
= ((sodium in mEq/L) + (potassium in mEq/L)) - ((chloride in mEq/L) + (HCO3 in mEq/L))
corrected anion gap =
= (observed anion gap) + (0.25 * ((normal serum albumin in g/L) - (observed albumin in g/L)) =
= (observed anion gap) + (0.25 * (44 - (observed albumin in g/L))

Abnormal LFTs

Hepatocellular injury: increase in ALT and AST (AST more in alcoholic liver disease, ALT more in viral hepatitis), (+/-) ALP and Tbili
Cholestasis: increase in ALP and Tbili, (+/-) ALT and AST
Isolated hyperbilirubinemia: increase in Tbili, normal transaminases and ALP

Liver Disease

Acute: First presentation is transaminitis (AST, ALT), ALP (if any obstruction presents)
Chronic: ALT and AST elevated for more than 6 months-> increase bilirubin-> decrease in albumin-> decrease in platelet count-> coagulation factors

Isolated Hyperbilirubinemia

1) Unconjugated:
a) Over production: hemolytic anemia
b) Defective conjugation: Gilbert's syndrome (jaundice when hungry), Crigler-Najjar
2) Conjugated
Defective excretion: Dubin-Johnson, Rotor's syndrome (black liver)

Acute vs. Chronic Renal Failure

DDx for Muscle Weakness

1) Muscle:
a) Congenital myopathies and mitochondrial myopathies: Sx. bilateral, proximal to distal wasting. Dx: elevated CK and LDH, abnormal EMG, normal nerve conduction. definite diagnosis with genetic testing.
b) Polymyositis: Abnormal CK and LDH, Dx with muscle biopsy
c) Dermatomyositis: Abnormal CK and LDH, Dx made with muscle biopsy
d) CREST syndrome: Anti-centromere ab
2) NMJ
a) Myesthenia gravis: Dx with EMG. Contractile force reduced with repetition
b) Lambart-Eaton: Dx with EMG. Contractile force increased with repetition
3) PNS
a) Diabetic Neuropathy: loss of sensation first. abnormal NC labs
b) Peripheral nerve degeneration/demyelination. Abnormal NC studies. Weakness in isolated motor neauron units
c) Radiculopathy: weaknes in motor neuron unit bundles. Abnormal NC studies
4) CNS
a) Gullian-Barre: ascending progression. increased ab levels in CSF
b) MS: lesions on CNS on MRI
c) B12 deficiency: depleted B12 levels
d) Polio
e) ALS: intact sensation, both upper neuron and lower neuron signs