Clinical biochemistry Flashcards
Why would FBCs be requested?
- Screen for a range of diseases
- Diagnose various conditions, e.g. anaemia, infection
- Monitor a condition/ effectiveness of treatment after diagnosis
- Monitor treatment known to affect blood e.g. chemotherapy or radiotherapy
What is included in a FBC?
White blood cells –> defence against infection and cancer, allergy and inflammation
Red blood cells –> transporters of oxygen through the body
Platelets –> responsible for blood clotting
What is CRP?
C-reactive protein
- An acute phase protein (concentrations increase or decrease by 25% or more during inflammation) produced by the liver
- High levels indicate inflammation in the body
- Reference range is 0-10mg/dL
What is albumin?
- An inflammatory marker/ marker of infection in many chronic disease states e.g. liver and renal disease
- Low levels are found in liver disease, severe inflammation
- High levels are found in dehydration
- Normal range is 35-55g/l
What is an acute phase response?
The body’s response to inflammation resulting in a rise or decrease in plasma concentration of acute phase proteins.
E.g. positive –> CRP, ferritin
Negative –> albumin, tranferrin
Changes in these parameters may be used as markers of inflammation
Why are U&E tests?
Urea and electrolytes
The. most commonly requested biochemistry tests providing essential information on renal function.
Urea is the excretory product of biochemical metabolism. It is synthesised by the liver and is a good marker of acute renal disease.
What is creatinine?
Product of protein breakdown, useful marker of long term renal function
What is renal disease glomerular filtration rate>
Kidney function test
The rate at which blood is filtered by passing over the glomerulus to begin urine production.
Chronic kidney disease is stage 1-5 based on eGFR
What do electrolytes do in the body?
- Help move nutrients into cells
- Help remove waste products from cells
- Maintain fluid balance
- Help stabilise levels of acid and alkali in the body (pH balance)
What is a raised sodium level called?
Why could it occur?
Hypernatraemia
Could be the result of dehydration or persistent diarrhoea
What is low sodium?
Why could it occur?
Hyponatraemia
Could be due to certain medication such as diuretics.
Rare –> from diabetes insipidus
Why might potassium levels be raised?
Name?
Hyperkalaemia
Could be a result of kidney failure
Certain medications can raise potassium levels, e.g. ACE inhibitors which are hypertensive drugs
Why might potassium levels be low?
Name?
Hypokalaemia
Could be result of persistent vomiting or diarrhoea
Also can be due to certain medications
Discuss calcium
Most concentrated in blood.
Some bound to albumin
High levels found with hyperparathyroidism, metastatic calcium, myeloma and dehydration
Low levels found with hypoparathyroidism, vitamin D deficiency, chronic renal failure, hypoalbuminaemia, acute pancreatitis, cirrhosis
Discuss phosphate
An inverse relationship exists between levels of phosphate and calcium, if the serum level of one rises, the other falls.
Plays important role in how the body uses carbohydrates and fats. It is also needed for the body to make protein for growth, maintenance, and repair of cells and tissues.
Phosphorus also helps make ATP
Why might phosphate levels be low?
- Re-feeding syndrome
- Impaired intestinal absorption
- Increased renal excretion
- Increased bone storage
Why might phosphate levels be raised?
- Renal failure
- Dehydration
- Cirrhosis
- Bone calcium
- DKA
Why might magnesium levels be raised?
- Advanced renal failure
Why might magnesium levels be low?
- Re-feeding syndrome
- Impaired intestinal absorption
- Haemodialysis
- Associated with calcium and potassium deficiencies
Discuss magnesium
Serum Mg level is maintained by function of GI absorption and excretion and renal resorption and excretion.
Magnesium regulates muscle and nerve function, blood sugar levels and blood pressure. It is also involved in make protein, bone and DNA.
Who is at risk of re-feeding syndrome?
1 or more
- BMI less than 16kg/m2
- Unintentional weight loss greater than 15% within the last 3-6 months
- Little or no nutritional intake for more than 10 days
- Low levels of potassium, phosphate or magnesium prior to feeding
2 or more
- BMI less than 18.5kg/m2
- Unintentional weight loss greater than 10% within the last 3-6 months
- Little or no nutritional intake for more than 5 days
- A history of alcohol abuse or drugs including insulin, chemotherapy, antacids or diuretics
What are some clinical manifestations of re-feeding syndrome?
Low phosphate, potassium and magnesium
How should re-feeding syndrome be prevented in hospital?
- Start nutrition support at a maximum of 10kcal/kg/day, increasing levels slowly to meet or exceed full needs by days 4-7.
- Using only 5kcal/kg/day in extreme cases (e.g. bmi less than 14kg/m2 or negligible intake for more than 15 days
- Continually monitoring cardiac rhythm
- Monitoring fluid balance and overall clinical status closely
- Providing immediately before and during the first 10 days of feeding –> oral thiamine 200-300mg daily, Vitamin B (may require IV) and a balanced multivitamin/ trace element supplement once daily.
- Providing oral, enteral or IV potassium (2-4 mmol/kg/day), phosphate (0.3-0.6 mmol/kg/day) and magnesium (0.2mmol/kg/da7), unless pre-feeding plasma levels are high.
What do LFTs show?
When liver is damaged it releases enzymes into the blood and levels of proteins e.g. albumin that the liver produces begin to fall.
By measuring levels of these enzymes and protein its is possible to understand how well the liver is functioning.
- Alanine aminotransferase (ALT)
- Aspartate aminotransferase (AST)
- Gamma-glutamyltranspeptidase (GGT)
- Albumin
- Bilirubin
What is the normal range of Hba1c?
Below 42mmol/mol
Prediabetes 42-47mmol/mol
Diabetes 48 mmol/mol or over
