other_chemistry
Other Electrolytes
Hypophophataemia
- redistribution - associated with major surgery fluid shifts, insulin/glucagon/adrenaline use, respiratory alkalosis
- beware esp in Rx of hyperglycaemia, DKA (osmotic losses + redistribution with insulin)
- decreased absorption - malnutrition, alcohol Xs, anorexia
- increased renal loss - associated with diuretics
- renal replacement therapies - loss in effluent with large fluid shifts
- Clinical - muscle weakness, CNS changes, poor WCC function reducing resistance to infection, arrhythmias
- Treatment - depends on level:
- <0.64mmol/l & asymptomatic - preferably enteral replacement (Phosphate Sandoz tablets contain 500mg elemental phosphorous - 4-6 tablets daily for adults, 2-3 for kids)
- <0.32mmol/l or symptomatic - parenteral replacement
Liver Function Tests (LFTs)
| AST | • raised in proportion to cellular damage and especially early stage of necrosis • found in cardiac and skeletal M, kidney, brain, pancreas and red cells and therefore ??? in skeletal M trauma and other Muscle disorders, MI, hepatitis etc |
|---|---|
| ALT | • levels not related to degree of liver necrosis and not useful in prognosis • more specific than AST for liver damage • higher levels seen with chronic hepatitis, cholestasis, CCF, infectious mononucleosis, various drugs eg paracetamol, phenothiazines, barbiturates, morphine, tetracyclines • isolated elevated ALT - consider rechecking in >6/12. If remains high - then Ix for hepatocellular disease • remember that 'normal' range is just that - Bell curve means that 2.5% pop will be outside 'normal' range |
| AST:ALT <1 | • viral hepatitis • severe toxic hepatitis • ischaemic hepatitis |
| AST:ALT >2.5 | • classic alcoholic liver disease with acute hepatocellular injury • active cirrhosis |
| ALP | • primarily biliary stasis/obstruction and malignancy • also a marker of bone turnover and therefore seen with bony disorders & metastases • normally high in late pregnancy |
| dGT | • sensitive to alcohol ingestion and especially with biliary obstruction • also raised in pancreatitis, brain tumours, renal and prostatic disease and post MI |
| LDH | • found in most tissues • especially raised in CCF, PE's and infarction, anaemias, hepatitis StatPearls 2021 LDH biochem |
Summary of enzyme patterns in Liver Disease |
|||||
|---|---|---|---|---|---|
| ALP | AST | ALT | dGT | other | |
| Cholestasis | ↑↑ | ↑ | ↑ | ↑↑ | AST:ALT<1.5 suggests extrahepatic, >1.5 suggests intrahepatic |
| Prim Biliary Cirrhosis | ↑↑↑ | ↑/N | ↑/N | ↑↑ | raised AST:ALT suggests cirrhosis |
| Prim sclerosing cholangitis | ↑↑ | ↑/N | ↑/N | ↑↑ | AST:ALT>1 may suggest cirrhosis >1.12 suggests risk of varices |
| Alcoholic Liver Disease | ↑/N | ↑ | ↑ | ↑↑ | AST:ALT>2 |
| NAFLD/NASH | ↑/N | ↑ | ↑ | ↑ | AST:ALT<1 unless cirrhosis |
| Wilsons disease | ↑ | ↑↑ | ↑↑ | ↑ | ALP:bili<4, AST:ALT>2.2 |
| Hep B, C | ↑ | ↑↑/N | ↑↑/N | ↑ | AST:ALT>1 suggests cirrhosis AST:platelets>1.5 suggests moderate fibrosis enzymes may all be N |
| Autoimmune Hepatitis | ↑ | ↑↑ | ↑↑ | ↑ | persistently high transaminases suggests poor prognosis |
| Ischaemic/shock injury Toxic injury | ↑ | ↑↑↑ | ↑↑↑ | ↑ | |
vit B12
paradoxically accompanied by signs of deficiency, - a functional deficiency linked to qualitative abnormalities,eg. defects in tissue uptake and action of vitamin B12 high levels not infrequently associated with solid tumours:
- myeloproliferative blood disorders
- hepatocellular carcinoma (HCC) and secondary liver tumours
- breast cancer, colon cancer, cancer of the stomach and pancreatic tumours.
Author: Dr Dylan Jenkins Oct 2023