Clinical Biochemistry

Question 1

Biochemical markers for muscle damage?

Answer 1

Creatine kinase 
Lactate dehydrogenase
Myoglobin 
AST 
Troponin

Question 2

Myotonia?

Answer 2

Inability of muscle to relax after contraction

Question 3

Rhabdomyolysis?

Answer 3

Breakdown of muscle fibres with increased CL

Question 4

Dystrophy?

Answer 4

Is progressive abnormality

Question 5

Causes of increased CK?

Answer 5

X 10 more upper limit of normal- MI, duchenne muscular dystrophy, rhabdomyolysis, polymyositis

X5-10- post surgery, trauma, sever exercise, grand mal convulsion, myosotis, carriers of duchenne muscular dystrophy

X5- physiological, hypothyroidism and drugs (statins, 1 in 10,000)

Question 6

Rhabdomyolysis results in release of?

Answer 6

Myoglobin and other muscle proteins and intracellular ions into circulation

Question 7

Skeletal muscle contribute to what percent of body weight?

Answer 7

40

Question 8

Causes of rhambdomyolysis?

Answer 8

Severe exercise
 Injury
Ischaemia
Metabolic: McArdles disease, Malignant Hyperpyrexia, hypokalaemia, hypophosphatemia
Infection
Toxin 
Drugs

Question 9

Rhambdomyolysis serum shows?

Answer 9

Hyperkalaemia
Hyper phosphatemia 
Hyperuricaemia
Hypocalcaemia
Rise in creatinine
Metabolic acidosis 
CK> x 10 ULN
Urine dip positive for activity of myoglobin

Question 10

Renal failure in rhabdomyolysis caused by?

Answer 10

Hypovolaemia hyperuricaemia
Aciduria- causes myoglobin to convert to ferrihaemate (nephrotoxic and it precipitates)

Metabolic acidosis hypovol
Dehydration increases urine conc and tubular obstruction by myoglobin casts Uris acid casts

Question 11

Renal protection in rhabdomyolysis?

Answer 11

Give fluids,
Less common-

Mannitol- osmotic diuretic
Urine alkalinasation because most casts are produced in acid urine
Early hemofiltration

Question 12

Biochemical investigations of muscle disease?

Answer 12

Plasma sodium, potassium, chloride etc

Plasma creatine kinase activity

ALT/AST (ALT increases in muscle disease)

Myoglobin in urine

Fatty acids, carnitine

Question 13

Metabolic muscle disease?

Answer 13

1, carbohydrate metabolism

2. Respiratory chain
3. Fatty acid oxidation

Question 14

Symptoms of metabolic muscle disease?

Answer 14

Most in early life
Exercise intolerance mild to fatal 
Muscle pain after exercise
Cramps
Muscle damage 
Rhabdomyolysis 
Proximal muscle weakness
Hypotonia 
Other organs affected
Myoglobinuria

Question 15

Carbohydrate metabolism muscledisorders signs and examples?

Answer 15

Cardiomegaly 
Hepatomegaly
Macroglossia
Respiratory dysfunction 
Progressive weakness with atrophy

E.g glycogen storage disease McArdle

Pompe

Question 16

Defects of respiratory chain signs?

Answer 16

Cardiomyopathy, muscle weakness, exercise intolerance, hearing loss, seizures, ataxia, pigmentary retinopathy

E.g MELAS- maternal inheritance

Merrf, kearns sayre

Question 17

Defects of fatty acid oxidation, lipid storage disease symptoms signs?

Answer 17

Muscle weakness and pain, myoglobinuria exercise intolerance symptoms present after prolonged period of exercise

Question 18

Duchenne muscular dystrophy?

Answer 18

Dystrophin gene x linked recessive

Proximal weakness, gowers sign, hypertrophy, contractures

Question 19

Lab results for duchenne muscular dystrophy?

Answer 19

Very high CK

Question 20

Myasthenia gravis is due to?

Answer 20

Antibodies to AchR

Question 21

Signs of myasthenia gravis?

Answer 21

Diplopia and ptosis

Question 22

Who does myasthenia gravis occur in?

Answer 22

Young women, those with thymoma

Question 23

Lambert Eaton myasthenic syndrome?

Answer 23

Antibodies against presynaptic voltage gated calcium channels

Can’t release acetylcholine

Rare

Question 24

DMARDS methotrexate?

Answer 24

PIIINP type III pro collagen peptide, marker of liver fibrosis, indicates if you needs liver biopsy for those on long term methotrexate

Question 25

Azathioprine?

Answer 25

Thiopurine methyl transferase transfers into inactive products, make sure If TMPT levels are low that you use a lower dose of drug

Question 26

Bone turnover markers?

Answer 26

Osteolysis- serum CTX and urinary NTX

Osteogenesis- ALP and P1NP

Question 27

Indicator of bone resorption?

Answer 27

CTX c-telopeptide of type 1 collagen

Question 28

Indicator of bone formation?

Answer 28

PINP- n-propeptide of type 1 collagen

Question 29

Gout affects how many adults?

Answer 29

1%

Question 30

Secondary causes of gout?

Answer 30

Hypothyroidism, hyperparathyroidism,, aspirin, renal impairment, thiazides diuretics

Question 31

What happens to solubility of Uric crystals?

Answer 31

Low pH and low temp and affected by concentration of other ions

Question 32

First line treatment of gout?

Answer 32

Allopurinol, stops xanthine oxidase which converts to xanthine to uric acid

Question 33

Probenecid and sulphinpyrazone to control gout?

Answer 33

Increase secretion of uric acid in kidneys

Question 34

Osteomalacia?

Answer 34

Incomplete mineralisation as Ostiod is laid down

Question 35

Rickets causes?

Answer 35

Widened growth plate and widened metaphysis

Question 36

Osteomalacia causes?

Answer 36

Vit d deficiency

Abnormal vit d metabolism

Low phosphate - low intake/ excess losses

Question 37

Signs of osteomalacia

Answer 37

Malaise, bone pain, proximal muscle weakness, myopathy

Question 38

Clinical values for osteomalacia?

Answer 38

All phosphates high, ca low/ normal, phosphate low/normal

Looser zones in x rays

Question 39

Rickets type 1 has?

Answer 39

Low 1,25 d- active form, due to renal failure

Question 40

Rickets type 2?

Answer 40

Have 1,25 d but no receptor for it

Question 41

Pagets disease?

Answer 41

Focal disorder of bone remodelling, accelerated bone turnover, increased osteoclast, weakened disorganised enlarged

Question 42

Features of pagets?

Answer 42

Raised ALP , bone pain, bone enlargement, fractures etc

Question 43

Kocher debre semelaigne syndrome?

Answer 43

Untreated hypothyroidism