CHEMPATH: Clinical chemistry CPC Flashcards
Which of the following is associated with depression?
- Hyperkalaemia
- Hypokalaemia
- Hypercalcaemia
- Hypocalcaemia
- Uraemia
- Hypocalcaemia –> irritability and fits;
- Hypercalcaemia –> subtle tiredness, depression
Calcium, in general, affects the brain and nervous system
- Potassium affects heart before neurones –> heart becomes irritable –> arrhythmias (VF)
- As potassium rises, myocardium becomes more stable, however, the ultimate stable rhythm = asystole
- Answer:
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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
-
Smith’s fracture = posterior displacement of the radius (i.e. radius** towards the **BACK of the hand)
Other:
-
Colle’s fracture = anterior displacement of the radius (i.e. radius** towards the **PALM of the hand)
* Falling on an extended wrist- Pott’s fracture = ankle fracture involving both tibia and fibula
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Colle’s fracture = anterior displacement of the radius (i.e. radius** towards the **PALM of the hand)
What do these results show?
Haematuria
What is the cause of massive haematuria in this patient? (with hypercalcaemia, depression, fracture and blood in urine)
- Renal stone
- Glomerulonephritis
- DKA
- Acute rheumatic fever
- Subacute bacterial endocarditis
Renal stones (or glomerulonephritis)
- Renal stones –> tear urothelium –> macroscopic haematuria
- Glomerulonephritis –> microscopic haematuria (not overt)
- DKA –> acidosis, ketonuria
- Acute rheumatic fever –> proteinuria (or normal)
- Subacute bacterial endocarditis à microemboli, microscopic haematuria, splenomegaly
How do you investigate calcified renal stones?
- Investigated with:
- Plain abdominal XR –> calcified stones (can be confused with gallstones)
- USS abdomen –> nephrocalcinosis
N.B. do plasma calcium before PTH because you need the calcium level to interpret any PTH level
List 3 causes of Ca2+ levels of 2.82.
- Cancer
- Primary HPT
- Sarcoidosis
If the PTH level is 3.0 (1.1-6.8 pM) and Ca is 2.82, what is the cause?
PTH is INAPPROPRIATELY high for the Ca level.
This is a normal level so malignancy and sarcoid would be excluded as the high Ca would suppress PTH.
- 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)
What are the actions of PTH?
PTH actions:
- Kidneys:
- Activate 1-alpha hydroxylase = vitamin D activation:
- Absorb calcium from gut
- Absorb phosphate from gut
- Directly resorb calcium
- Directly excrete phosphate
- Activate 1-alpha hydroxylase = vitamin D activation:
- Bone:
- Activate osteoclasts
What are the features and complications of hypercalcaemia?
Band keratopathy shown on eye
What are the different types of kidney stones?
What are the risk factors for renal calcium stones?
- Risk Factors:
- FHx
- Dehydration
- Hypercalciuria
- Hypercalcaemia
- HPT
- Recurrent UTI
How do renal stones present?
- Pain
- Haematuria
- Recurrent infections (Proteus mirabilis)
- Renal failure
What Ix do you do for calcium renal stones?
- CT-KUB
- Stone analysis
- Urine and serum biochemistry
How do you manage renal stones?
- Most stones will pass –> painkillers:
- PR diclofenac is very good
- Lithotripsy
- Cystoscopy
- Lithotomy
How do you prevent renal stones?
- Drink more water
- Treat hypercalciuria (e.g. thiazides)
- Not in parathyroid adenoma –> hypercalcaemia (reduces calcinuria but increases serum Ca)
- Treat hypercalcaemia
How do you manage hypercalcaemia firstly?
Urgent treatment ([Ca2+] >3.0mmol/L ± unwell) – if calcium <2.8mmol/L, this doesn’t need to be as intense
-
FLUIDS –> IV 0.9% saline
- 4-hourly or 6-hourly bags of 1L 0.9% NaCl
- 1st bag of 1L given over 1 hour (if severely dehydrated)
- IV frusemide (prevent pulmonary oedema and aid calciuresis)
- MAYBE IV pamidronate (bisphosphonate), 30-60mg (if CANCER is the primary cause of the hypercalcaemia)
How is the primary hyperparathyroidism/hypercalcaemia managed in the long term?
- Well hydrated
- Avoid thiazides (reduce hypercalciuria but increase plasma calcium)
- Surgery (parathyroidectomy)
- Technetium Sesta MIBI and USS performed à shows hyperactive parathyroid
- If both tests concordant à whole neck does NOT need to be opened
- If tests not concordant à surgeon needs to view all four glands and take out the largest one
What does this bone histology show?
Brown tumours =
- multinucleate giant cells
- Activated osteoclasts in the bone
- long-standing undiagnosed HPT
What does the XR show in longstanding hypercalcaemia?
Radial cysic changes with longstanding hypercalcaemia (but initially normal)
NB: Looser’s zones are in longstanding Vitamin D deficiency/osteomalacia (needs to be very low). This is a pseudofracture.
What does this CXR show?
Bihilar lymohadenopathy
How does sarcoidosis cause hypercalcaemia?
Macrophages in the lungs express 1 alpha hydroxylase
Vitamin D leads to excessive calcium
Patients more likely to become hypercalcaemic in summer months because of increased exposure to sunlight
What is most increased in bloods in Paget’s disease? What about osteomalacia?
Alkaline phosphatase in bone (because increased osteoclast activity which release ALP)
What is increased in a patient with MI?
AST is most increased
Also release CK (due to damage, this activates enzymes), LDH, troponins.
What is the pathophysiology of Paget’s disease? What is the most useful imaging investigation?
Increased activity of both osteoclasts and osteoblasts –> increase in ALP and osteocalcin
Investigation: technetium bisphosphonate scan a.k.a. bone scan
Whata are the features of Paget’s disease?
- Features:
- Asymptomatic
- Bowed tibia (it will also be warm)
- High risk of fracture
What is increased in Addison’s disease?
K is high
Na is low
What is most raised in someone with gallstone?
ALP (alkaline phosphatase)
What is most raises in someone with jaundice caused by viral hepatitis?
ALT
What is raised most in someone with jaundice caused by alcoholic hepatitis?
AST
What is most increased in a patient with prostatic carcinoma?
Acid phosphatase a.k.a. PSA
What is raised in someone with primary HPT?
Calcium
What imaging is best used to look for abdominal metastases?
FDG-PET Scans – glucose uptake…
- Look for abdominal metastases
- Marker = FDG (fluorodeoxyglucose) –> scan is labelled as an FDG PET Scan
- Non-specific marker as glucose is taken up by ANY active cell
- Cancer cells are more active so they will take up more FDG
NB: Gallium 68 scan (with somatostatin analogue) used for neuroendocrine tumours.
Which technecium scan is used for the thyroid?
- Technetium 99m (pertechnetate) scan –> iodine uptake by thyroids
- Diffuse uptake = diffuse goitre / Graves’ disease
- Unilateral uptake / hot nodule = adenoma
What is the portal triad?
bile duct
portal vein
hepatic artery
Why is AST increased following acute MI?
- Increase following an acute MI (AST is found within the myocytes)
- AST goes up about 3 days after an MI and remains for around 14 days (3-14 days)
What are the indications for dialysis?
Indications for Dialysis:
- Refractory hyperkalaemia
- Refractory fluid overload
- Metabolic acidosis
- Uraemic symptoms (encephalopathy, nausea, pruritis, malaise, pericarditis)
- CKD stage 5 (GFR <15mL/min)
Whis the pathophysiology of rhabdomyolysis?
- Rhabdomyolysis –> acute kidney injury (because myoglobin is very nephrotoxic)
- Very high CK (from muscle breakdown) –> renal failure
- Prevention = IV bicarbonate, allows them to excrete extra CK
What is the transaminase ratio in chronic alcoholic cirrhosis?
AST will be higher than ALT (2:1) in patients with chronic alcoholic cirrhosis
NB: ALT will be higher than AST in patients with viral hepatitis
What rises most in acute vs chronic renal failure?
- In acute** renal failure caused by dehydration, **UREA will rise the most
- In chronic** renal failure that is caused by a fall in GFR, **CREATININE will rise the most
Name 2 markers of glucose control.
- Last 3 weeks = fructosamine
- It is important to have good diabetic control during pregnancy (cannot wait 3 months to assess HbA1c)
- As pregnancy progresses, you get more insulin resistance, so glucose control becomes more important
- FreeStyle Libre = a probe that you can put on your arm and swipe to get a reading
- Last 3 months = HbA1c
What is the management of Paget’s?
TREATMENT –> bisphosphonates (only if painful) – bone formed with Ca2+ bisphosphonate not degraded by osteoclasts
Describe how a Gallium 68 scan works.
- Could be an insulinoma
- Superimpose a radiolabelled scan using Gallium 68 (Gallium can be stuck onto a somatostatin analogue so that it goes to tissues that have somatostatin receptors; i.e. any neuroendocrine cell)
- AKA: Gallium DOTATATE scan
IMPORTANT: spleen has a lot of receptors for somatostatin so it will always appear hot (so, localisation in the spleen is a telling feature of Gallium 68 scans using somatostatin analogues)
- The kidneys, cysts in kidneys, and adrenals will also appear hot
What is a sesta MIBI/Sestamibi?
- Used by the parathyroids and myocardium
- I.E. in MI, you see an area of a lack of uptake of MIBI
Scans overview:
- Abdominal metastasis from cancer - FDG PET scan
- CT scan w/ contrast - Visualise anatomy (portal, venous, arterial)
- Bony metastasis / Paget’s - Tc bisphosphonate
- Thyroid scans - Tc 99m pertechnetate
- Neuroendocrine tumours (insulinomas, phaeo) - Gallium 68 dotatate
- Parathyroid scans - Sesta MIBI
- Phaeochromocytoma - MIBG (Meta-iodobenzylguanidine), Gallium dotatate
