Chemical Pathology Flashcards
The enzyme expressed by sarcoid lung tissue which causes hypercalcaemia
1a-hydroxylase (= rate limiting step in Vitamin D production!)
Costochondral swelling
Rickets
Looser’s Zones = pseudofractures
Osteomalacia
Colle’s Fracture
Osteoporosis
Band Keratopathy
Hypercalcaemia (calcium deposits on eyes)
Osteitis Fibrosa Cystica
Hypercalcaemia – get brown tumours in bone
Cancer which releases PTHrP
Small cell lung cancer
Brown tumours in bone
Hyperparathyroidism (activated osteoclasts form multinucleated giant cells)
Hypercalcaemia in summer only
Sarcoidosis (macrophages in lung express 1α-hydroxylase, but not enough Vit D in winter to activate)
Chvostek’s Sign
Hypocalcaemia = twitch when flick cheek
Trousseau’s Sign
Hypocalcaemia = inflate BP cuff causes carpal spasm
Jigsaw/mosaic pattern in bone
Paget’s Disease (disordered bone remodelling)
Most reliable sign of hypovolaemia in hyponatraemia, which must be done first (before giving fluids)
Low urine Na+ (<20)
Molecule causing vasodilation and low BP in cirrhosis
Nitric Oxide
Tendon Xanthoma
Familial hypercholesterolaemia
Eruptive xanthomas (papules on skin)
Primary Hypertriglyceridaemia
Diabetes
Gross xanthelasma
Primary Biliary Cirrhosis
Monoclonal used in hereditary hypercholesterolaemia
Evolocumab = PCSK9 monoclonal
Diabetes Control and Complications Trial (DCCT)
Type 1 DM: tight control improves outcomes
UK Prospective Diabetes Study (UKPDS)
Takes 15 years to have CVD benefit –> but this benefit lasts 10 years
ACCORD Study
Intensive treatment in older diabetics increases mortality
ADVANCE Study
Looser control works better in older people
Drug added to long-term poorly controlled diabetes with ESTABLISHED CVD
Empagliflozin (SGLT2 inhibitor) or liraglutide (GLP-1 agonist)
Breathing type in metabolic acidosis
Kussmaul Breathing (deep laboured)
Diabetes drug causing metabolic acidosis
Metformin (prevents lactase to glucose conversion)
3 definitions of diabetes
- Fasting PLASMA glucose > 7.0mM
- Plasma glucose after GTT > 11.1mM at 2hrs
- HbA1c > 6.5% (48mmol/mol)
Impaired Glucose Tolerance definition
Plasma glucose after GTT 7.8 – 11.1mM at 2hrs
Low blood glucose, but high C-peptide. What test should you do?
Check urine sulphonylurea as could have OD’d on gliclazide (endogenous insulin)
Non-Islet Cell Tumour secrete which hormone, causing hypoglycaemia
IGF-2 (binds to insulin receptors, acting like insulin)
e.g. mesothelioma, fibroblastoma…
Mutation causing congenital hyperinsulinism = hypoglycaemia
Glucokinase activating mutations
Glucocorticoids secreted by which part of adrenal?
Zona fasciculata
Androgens secreted by which part of adrenal?
Zona reticularis
Aldosterone secreted by which part of adrenal?
Zona glomerulosa
Short SynACTHen test
Addison’s Disease (don’t make enough cortisol after given synACTH)
Syndrome which increases risk of phaeochromocytoma
MEN II
High aldosterone and low renin
Conn’s (high aldosterone suppresses JGA –> low renin)
High aldosterone and high renin
Renal artery stenosis
Brown granular casts in urine
Acute Tubular Injury
Crescents in glomeruli
Crescent Glomerulonephritis (Acute Glomerulonephritis)
Disease causing renal failure, with non-blanching purpuric rash
Systemic Vasculitis
Drugs which prevent end-stage renal failure
ACEi
Cause of nephrotic syndrome in kids
Minimal Change Disease – have loss of foot process
Antibodies in Membranous Glomerulonephritis
Antibodies against phospholipase A2
Renal disease with microalbuminuria
Diabetic nephropathy
Beta-pleated proteinaceous sheets deposited in kidneys
Amyloidosis
Protein found in urine of multiple myeloma
Bence-Jones
Crystals in urine after drink antifreeze
Calcium oxalate
Sample blood from this vein to measure levels of illegal drugs
Femoral vein
Which drug cannot be found in hair?
Cannabis (too low levels)
Active metabolite of amitriptyline
Nortriptyline
AST : ALT >2
Cirrhosis
Half-life of albumin
20 days (“important to know this”)
Most important functional test of liver
Prothrombin Time
Tumour marker in liver cancer
AFP
Beri-Beri caused by what deficiency?
B1 (thiamine)
Pernicious anaemia caused by what deficiency?
B12
Glossitis (beefy tongue) caused by what deficiency?
B2
Test of B12 deficiency
RBC Transketolase
Most common co-existing autoimmune condition in hypothyroid
Pernicious anaemia
Condition with:
- Tricuspid and pulmonary stenosis/fibrosis
- Hepatomegaly with large nodules
- Raised urine 5HIAA
Carcinoid Syndrome = tumour in neuroendocrine cells
Colourless urine gets oxidised to purple before reaches the lab
Porphyria (porphyrinogens = colourless –> oxidised very quickly by UV light in urine)
Porphyria with blistering on backs of hands
Hereditary Coproporphyria (HCP)
Light hair and mousy/musky urine odour
Phenylketonuria (PKU)
Deficiency of what enzyme in Phenylketonuria?
Phenylalanine hydroxylase
Metabolic disease causing cot death
MCAD Deficiency
Baby smells of sweaty feet
Isovaleric Acidemia
Urine smells sweet
Maple Syrup Urine Disease
What drug triggers Reye Syndrome?
Aspirin (salicylates)
10yo girl hirsutism, low cortisol, raised ACTH and 17 hydroxyprogesterone
Congenital Adrenal Hyperplasia = lack 21-hydroxylase
Polysplenia and situs inversus
Biliary atresia
Ambiguous genitalia in neonates
Congenital Adrenal Hyperplasia (increased 17-OH progesterone –> increased androgens)
Frontal bossing in kids
Rickets
Caput medusa
Portal HTN (blood goes back down portal vein to umbilicus)
Gilbert’s caused by deficiency in which enzyme?
UDP glucuronyl transferase
Mode of inheritance in Gilbert’s
Autosomal recessive
Rate-limiting step of purine metabolism?
PPRP to 5-phosphoribosyl-1-amine (via PAT)
- PAT under feedback control by ANP and GNP
- HPRT = enzyme which helps make ANP and GNP
Gouty arthropathy, retarded and self-mutilates
Lesch Nyhan Syndrome (X-linked disease –> males born with no HPRT at all)
Gout crystals
Monosodium urate
Name of acute gout
Podagra
Cheesy ear lobes and gouty arthropathy
Chronic gout = tophaceous
Pseudogout crystas
Calcium pyrophosphate
Negatively birefrigent, needle-shaped
Monosodium urate
Positively birefringent
Calcium pyrophosphate (pseudogout)
Crystals in same axis of polarised light
Calcium pyrophosphate (pseudogout)
Crystals perpendicular to axis of polarised light
Monosodium urate (gout)
Allopurinol inhibits which enzyme?
Xanthine oxidase
Never mix allopurinol with what other drug?
Azathioprine (allopurinol interacts with azathioprine metabolism –> makes it last longer in body
–> toxic on bone marrow)
Form of Vitamin D made after action of 1a-hydroxylase on 25-OH D3?
Calcitriol = active form of Vitamin D
Hormone which stimulates 1a-hydroxylase in kidneys to increase Vitamin D3 production
PTH
23 year old who has just started penicillin. Presents with confusion, weakness and seizures. Pale, bruised and breathing deeply.
Acute Tubulointerstitial Nephritis
45 year old female with swelling ankles and abdomen. Urine dipstick +++ protein, no blood. Microscope shows thichening of GBM
Membranous Glomerulonephritis
7yo boy with swelling of legs and sacrum. Urine dipstick ++ proteinuria, no blood
Minimal Change Disease
25yo male sees blood in urine. Microscope shows mesangial cell proliferation
Mesangiocapillary Glomerulonephritis
45yo female with swelling ankles, abdomen. Urine dipstick +++ protein, no blood. Microscope shows segmental scarring of glomeruli
Focal Segmental Glomerulosclerosis
Child with excessively sweaty feet
Also: lethargy, poor feeding, hypotonia
Maple Syrup Urine Disease
“Cherry-red spot” in which group of disorders?
Lysosomal Storage Disorders
Overdose of this medication causes hypotension and ataxia
Phenytoin
Cortisol not suppressed by low-dose dexamethasone, but suppressed by high-dose
Cushing’s Disease
Increased levels are seen in the urine of CAH patients
Pregnanetriol
Sore throat a few days ago –> smoky-colour urine, puffy face, tired
Acute Proliferative Glomerulonephritis (post-streptococcal glomerulonephritis)
Sore throat –> proliferation of mesangium, microscopic haematuria
IgA nephropathy
-proliferation of mesangium is characteristic
Gold-standard for measuring GFR
Inulin
What vitamin deficiency in “Muslim woman”?
Vitamin D Deficiency (Muslim woman = hijab!)
Enzyme raised in mumps
Amylase
Deficiency of this vitamin causes triad of “3 D’s” = diarrhoea, dermatitis, dementia
Niacin
End-stage renal failure, with high PTH and high calcium
Tertiary hyperparathyroidism
Serum electropheresis shows monoclonal band
Multiple Myeloma
Pain and stiffness in lower back and bum – worse in morning, but eases as day goes by
Ankylosing Spondylitis
Serum electropheresis shows IgM spike
Waldenstrom’s Macroglobulinaemia
A 50 year male with multiple myeloma comes to his GP complaining of ankle swelling. Urine dipstick shows proteinuria. On examination he is also noted to have macroglossia and waxy papules on his face.
Amyloidosis
Raised anti-streptolysin O titre (ASOT)
Post-strep glomerulonephritis
Which type of strep is involved in post-strep glomerulonephritis?
Group A beta-haemolytic strep (Strep Pyogenes = preceding pharyngitis)
Immunofluoresence of GBM –> granular staining
Immune complex subtype of Rapidly Progressive Glomerulonephritis
Immunofluoresence of GBM –> absent/scant staining
Pauci-immune subtype of Rapidly Progressive Glomerulonephritis
Immunofluoresence of GBM –> linear staining
Anti-GBM subtype of Rapidly Progressive Glomerulonephritis
Kveim Test
Sarcoidosis (inject sample of spleen from known sarcoid patient into suspected sarcoid patient –> non-caseating granuloma after 6 weeks)
NOT used in UK!
X-Ray shows punched-out lytic lesions in bones
Multiple Myeloma
Side effect of medication: course tremor and diarrhoae
Lithium
Side effect of medication: prolonged PR interval
Digoxin
Bone pain in arms and legs
Shooting pains down left leg
Worsening SOB
Paget’s! (weak woven bone infiltrate bone marrow –> high-output heart failure)
Tall P waves and flattened T waves
Hypokalaemia
Boy with episodic abdominal pain and recurrent acute pancreatitis. Plasma has milky appearance and chylomicrons are found in the plasma following a period of fasting.
Lipoprotein lipase deficiency
Cause of pseudo-Vitamin D deficiency
Defect in renal hydroxylation
3-week old boy with severe jaundice at birth, worsening ever since
Crigler-Najjar syndrome = defect in bilirubin metabolism
First-line test when screening for metabolic diseases
Amino acids (urine and plasma)
A male infant presents with failure to thrive, neurological signs (including tremor) and tachypnea - what metabolic defect?
Urea Cycle Disorder (neuro signs + tachypnoea = encephalopathy + alkalosis = increased ammonia!)
Metabolic disorders causing jaundice and sepsis
Galactosaemia and tyrosinaemia
Deficiency that causes Wernicke’s
Thiamine (B1)
Cause of acute intermittent porphyria
PBG Deaminase Deficiency
-attacks triggered by alcohol, COCP and TB meds
Anion gap formula
Na + K – Cl - Bicarb
Osmolality formula
2(Na+K) + U + G
Newborn starts drinking milk –> conjugated hyperbilirubin, cataracts and GI symptoms
Galactosaemia (mutation in enzyme –> increased galactose when start drinking milk)
Nutritional deficiency causing rash in necklace formation
Niacin = B3 –> pellagra (4 D’s = Diarrhoea, Dermatitis, Dementia, Death)
High-dose dexamethasone suppression test –> high ACTH and cortisol
Ectopic ACTH causing Cushing’s syndrome
NOT pituitary-dependent Cushing’s Disease as would have low cortisol after high-dose dex
Abdo pain with bruising below umbilicus/on flank
Acute Pancreatitis
- Below umbilicus = Cullen’s Sign
- On flank = Grey-Turner Sign
Haemorrhage which features lucid interval
Extradural
Severe headache – fundoscopy reveals preretinal (subhyaloid) haemorrhages; CSF shows xanthochromia. Palpable kidneys bilaterally.
Subarachnoid Haemorrhage
-“palpable kidneys” = Polycystic!
Cause of episodic diarrhoea in long-term diabetic
Autonomic Neuropathy
Metabolic disease with abnormally long limbs and flushed cheeks
Homocystinuria
Illegal drug which increases CK
Ecstasy
Enzyme defect in Homocystinuria
Cystathionine beta synthase
Most common autoantibody in Hashimoto’s
Anti-thyroid peroxidase
Propylthiouracil (PTU) inhibits this
Thyroid peroxidase
Psychiatric drug which increases calcium
Lithium
Severe hypoglycaemia (symptoms worse after exercise) with sudden weight gain
Insulinoma
Doege-Potter Syndrome
Paraneoplastic where tumour secretes IGF2 –> low glucose
Test to distinguish between chronic and acute liver disease
Albumin
Liver enzyme raised after MI
AST
Immune deposits on the outside of GBM showing “spike and dome” pattern
Membranous Glomerulonephritis
Sharp cramping pain in the back radiating to the groin
Ureteric stones (renal stones have LOIN to groin)
What is Nelson’s Syndrome?
Remove adrenals due to Cushings –> Addisonian symptoms
Cushingoid, but pituitary and adrenals are normal. Heavy drinker
Pseudo-Cushings = caused by alcoholic liver disease and psych conditions
This hormone causes 1-alpha hydroxylation
PTH
Increases intestinal calcium reabsorption
Calcitriol (1,25 (OH)2 vitamin D)
High PTH, low calcium and high phosphate – hands look weird
Pseudohypoparathyroidism = resistance to PTH
hands look weird = blunting of 4th and 5th knuckles
Decreased faecal elastase
Pancreatic Insufficiency (chronic pancreatitis, CF…)
Rate-limiting enzyme in haem synthesis
ALA synthase
Where is B12 absorbed?
Terminal ileum (IBD with terminal ileum resection affected)
Where is iron absorbed?
Duodenum and jejunum
1st step of Vitamin D metabolism
Sunlight converts 7-dehydrocholesterol to cholecalciferol (D3)
What is 25-OH-D3?
Calcidiol
Where is 25-OH-D3 (calcidiol) made?
Liver: D3 hydroxylated to 25-OH-D3
What is active form of Vitamin D?
Calcitriol = 1,25-(OH)2-D3
Where is calcitriol made?
Kidneys: Calcidiol (25-OH-D3) converted by 1a-hydroxylase to calcitriol (1,25-(OH)2-D3)
What hormone triggers formation of calcitriol in kidneys?
PTH
Where is Vitamin D absorbed in gut?
Jejunum
Sodium and potassium balance in diuretic use
Lose sodium, retain potassium
Treatment of PBC
Bile acid sequestrants (cholestyramine)
Normal anion-gap metabolic acidosis
Bicarb loss from GI/kidneys (replaced by chloride)
Cause of Familial Hypercholesterolaemia
Deficiency in LDL receptor
Drug used to reduce triglycerides
Fibrates (gemfibrozil)
Lipoprotein lipase/apo-C deficiency
Increased chylomicrons and VLDLs
Diuretic which increases renal stones
Loop diuretic = increases calcium in urine
Diuretic which treats chronic renal stones
Thiazide diuretic (bendroflumethazide) = increases calcium reabsorption
Diuretic which causes hyperkalaemia
Spironolactone = aldosterone antagonist (all other diuretics cause low Na and K)
Posterior pituitary makes …
ADH and oxytocin
Metabolic disorder causing very fair skin, brittle hair and convulsions
Homocystinuria
Metabolic disorder causing excessively sweaty feet
Maple Syrup Urine Disease
Baby with dysmorphia and cherry-red spot on trunk
Fabry’s Disease (cherry-red spot = lysosomal storage disorder)
Drugs which cause isolated rise in GGT
Enzyme-inducing drugs (carbamazepine, phenytoin)
Drug which increases PR interval and causes bradycardia
Digoxin
Test to differentiate between primary and secondary Addison’s
Long synACTHen test (after 24hrs: cortisol <900 is primary)
Corrected calcium formula
Serum calcium + 0.02(40-serum albumin)
MEN type associated with hyperparathyroid
MEN 1 (= pit, para, panc)
Organ that releases angiotensinogen
Liver
This converts angiotensinogen to angiotensin 1
Renin
Aldosterone acts on what in kidneys?
Mineralocorticoid receptor on principal cells in cortical collecting tubules
Main cause of hyperkalaemia
Renal impairment (less K excreted)
Gliptins inhibit this
DPP4 (DPP4 breaks down GLP-1)
Consequence of hyperventilation in respiratory alkalosis
Low ionised calcium –> tetany
Area of adrenal which releases adreanline
Medulla
This provides negative feedback on prolactin
Dopamine
TRH increases TSH and what else?
Prolactin
Components of Combined Pituitary Function Test
- Insulin
- TRH
- LHRH
Normal Combined Pituitary Function Test results
- Glucose <2.2
- Cortisol 550
- GH 10
First-line investigation in acromegaly
Glucose Tolerance Test (GTT) = GH stays >2 when should be suppressed
Histological feature of minimal change disease
Loss of foot process
Main cause of drug-induced cholestasis
Co-amoxiclav
Cause of Acute Intermittent Porphyria
HMB synthase deficiency (autosomal dominant)