Clinical Chemistry CPC Flashcards by Can I get Uhhhh?

What is an alternative treatment to antidepressants?

CBT

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What is St John’s Wort?

(Hypericum perforatum)
o Thought to be quite similar to paroxetine (an antidepressant)
o The St. John’s wort was moderately effective

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What mood is hypercalcaemia associated with?

Depression/ tiredness

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What is hypocalcaemia associated with?

irritability and fits

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What are the heart affects of potassium?

o In hypokalaemia, your myocardium becomes more irritable -> leads to arrhythmias
o As potassium rises, myocardium becomes more stable, however, the ultimate stable rhythm = asystole

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What are 3 important types of Fractures?

o Smith’s fracture = posterior displacement of the radius (i.e. radius towards the BACK of the hand)
Falling on a flexed wrist
Treated with manipulation under anaesthesia (MUA) and plaster

o Colle’s fracture = anterior displacement of the radius (i.e. radius towards the PALM of the hand)
Falling on an extended wrist

o Pott’s fracture = ankle fracture involving both tibia and fibula

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Does Glomerulonephritis present with pain?

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What are the differentials of abnormal urine dip?

Renal stones -> tear urothelium -> macroscopic haematuria

Glomerulonephritis -> microscopic haematuria (not overt)

DKA -> acidosis, ketonuria

Acute rheumatic fever -> proteinuria (or normal)

Subacute bacterial endocarditis -> microemboli, microscopic haematuria, splenomegaly

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How do you investigate abdo pain with haematuria?

Plain abdominal XR -> calcified stones (can be confused with gallstones but better for renal colic)

USS abdomen -> nephrocalcinosis

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How do you find out the cause for someones renal stones?

Cancer (commonest in hospital)
Primary HPT (commonest in community)
Sarcoidosis

o N.B. do plasma calcium before PTH because you need the calcium level to interpret any PTH level
o [Ca2+] = 2.82 (2.20-2.60)
o PTH = 3.0 (1.1-6.8 pM)
o As PTH is normal -> primary HPT most likely

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How do PTH and calcium behave in sarcoidosis, cancer and primary hyperparathyroidism?

Sarcoid -> PTH suppression/low (as produces lots of calcium which suppresses PTH)
Cancer -> PTH high (endogenous production) -> from PTHrP or invading bone cancer
1st HPT -> PTH normal/high (despite hypercalcaemia)

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If PTH is not suppressed despite hypercalcaemia what is going on?

Endogenous PTH production

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How often is the cause of hypercalcaemia with high PTH an adenoma?

85%

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What are the actions of PTH?

Kidneys:
• Activate 1-alpha hydroxylase -> vitamin D activation ->
o Absorb calcium from gut
o Absorb phosphate from gut

Directly resorb calcium
Directly excrete phosphate

Bone:
• Activate osteoclasts

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What are the features of hypercalcaemia?

o Moans, bones, groans and stones
 Many can be asymptomatic
 Calcium stones are radio-opaque, but urate stones are radio-lucent
o Polydipsia/polyuria (nephrogenic DI)  calcium acts like glucose to carry water with it via osmosis

o Band keratopathy (calcium deposition across the front of the eye)
 This is a feature of CHRONIC hypercalcaemia (so it cannot be hypercalcaemia of malignancy)

o	Complications:
	Renal stones			
	Peptic ulcer disease
	Pancreatitis			
	Skeletal changes
	Osteitis fibrosa cystica (i.e. pepper-pot skull)

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What are the risk factors for renal calcium stones?

FHx		
Dehydration
Hypercalciuria 
Hypercalcaemia
HPT		
Recurrent UTI

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How would renal calcium stones present?

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 Pain
 Haematuria
 Recurrent infections (Proteus mirabilis)
 Renal failure

What is the investigations for renal stones?

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 CT-KUB
 Stone analysis
 Urine and serum biochemistry

What is the management of renal stones?

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	Most stones will pass -> painkillers:
•	PR diclofenac is very good
	Lithotripsy 
	Cystoscopy
	Lithotomy

How do you prevent renal stones?

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 Drink more water
 Treat hypercalciuria (e.g. thiazides)
• Not in parathyroid adenoma -> hypercalcaemia (reduces calcinuria but increases serum Ca)
 Treat hypercalcaemia

What is the management of hypercalcaemia?

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IV 0.9% saline
IV frusemide
IV pamidronate 30-60mg (better if cancer)

How do you give fluid in hypercalcaemia?

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4-hourly or 6-hourly bags of 1L 0.9% NaCl

* 1st bag of 1L given over 1 hour (if severely dehydrated)

Why do you give frusemide?

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prevent pulmonary oedema and aid calciuresis

How do you give pamidronate?

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IV pamidronate (bisphosphonate), 30-60mg
• Not given in all circumstances
• Do not take effect for around a week and is not given in all circumstances
• Hold off to begin with as you can’t measure serum calcium and phosphate if given
o Do NOT hold off if hypercalcaemia due to cancer

What is the non urgent treatment of hypercalcaemia?

Well hydrated Avoid thiazides (reduce hypercalciuria but increase plasma calcium) Surgery (parathyroidectomy) * Technetium Sesta MIBI and USS performed -> shows hyperactive parathyroid * If both tests concordant -> whole neck does NOT need to be opened * If tests not concordant -> surgeon needs to view all four glands and take out the largest one

What may the hand X ray be like in HPT?

o Often be normal | o Later stages may show cystic changes in the radial aspect

What is the histology of HPT?

o Brown tumours = multinucleate giant cells  Activated osteoclasts in the bone o Brown tumours = long-standing undiagnosed HPT o I.E. Histology of the bone shows…  Brown tumours  Multinucleate giant cells

if high calcium and PTH normal, go for the parathyroids

* 45yo, Afrocaribean man, SOB * Most helpful investigation -> CXR -> bilateral hilar lymphadenopathy * Histology of biopsy -> non-caseating granulomas Diagnosis?

Sarcoidosis

What is the biochemistry in sarcoidosis?

* FBC -> [Ca2+] 2.82 (2.20-2.60) | * PTH suppressed to undetectable levels -> sarcoidosis picture

What is the treatment of sarcoidosis?

Steroids

What is the mechanism of hypercalcaemia in sarcoidosis?

'Seasonal hyercalcaemia' o Macrophages in the lungs express 1-alpha hydroxylase -> activate vitamin D o Vitamin D leads to excessive calcium o Patients more likely to become hypercalcaemic in summer months because of increased exposure to sunlight

MEN 1 or 2 can present with hypercalcaemia

What do potassium abnormalities do to the heart?

Hypokalaemia- VF | Hyperkalaemia- Asystole

Can PTH be normal in primary hyperparathyroidism?

Yes- inappropriately not suppressed

What is the rate limiting step in Vit D production?

1 alpha hydroxylase

What will the hand x ray of 1HPT show?

Radial aspect cystic changes

What are the symptoms of hypercalcaemia (HPT)?

Bones (fractures) Stones (kidney) Groans (psych) Moans (abdo pain, pancreatitis)

What are looser's zones linked to?

Vit D deficiency

How do giant cells get formed?

Failure of cell division adding nuclei to a single huge cell- can happen in many AI

What is the rate limiting step of Vitamin D production?

1 alpha hydroxylation

Clinical Chemistry CPC Flashcards

(41 cards)