Chem Path Flashcards
Osmolarity=
2(Na + K) + Urea + Glucose
Osmolar gap=
Osmolality (measured) - Osmolarity (calculated)
Normal less than 2
Anion Gap=
(Na + K) - (Cl +HCO3)
Normal= 14-18
Normal range of Na
135-145
Hyponatraemia Sx
N+V
Confusion
Seizures
Coma
True Hyponatraemia
Low osmolality
Causes of True Hyponatraemia
Hypervolaemic - Organ failure (CCF, Cirrhosis, Neophrotic)
Euvolaemic - Endocrine (HoTy, Adrenal insuf., SIADH)
Hypovolaemic - Loss (D+V, Salt losing neph., Diuretics)
Differentiating causes of Hypovolaemic HoNa
Urinary Na >20= renal (diuretic, Addison’s, Salt losing neph.)
Urinary Na less than 20= non renal (D+V)
SIADH feats
True, euvolaemic HoNa w/ Urinary Na >20
Urine osm >100! (usually > serum osm)
No adrenal, renal or thyroid dysfunction
Hypernatraemia Sx
Thirst
Confusion
Seizures + ataxia
Coma
Hypernatraemia causes
Hypovolaemic
Euvolaemic
Hypervolaemic
Hypovolaemic HyperNa causes
GI loss (D+V) Skin loss (sweating, burns) Renal loss (loop diuretics, osmotic diuresis, renal disease)
Euvolaemic HyperNa causes
Resp loss (tachypnoea) Skin loss (sweating, fever) Renal loss (Diabetes insipidus)
Hypervolaemic HyperNa causes
Mineralocorticoid excess (Conn's) Hypertonic saline infusion
Diabetes insipidus
Polyuria, polydipsia + dilute urine (osm less than 2)
8 hour fluid deprivation test
Normal - Concentrate urine >600 osm/kg
Primary polydipsia - Concentrate urine >400-600
Cranial DI - Concentrate urine after desmopressin
Nephrogenic DI - No urine concentration
Potassium normal range
3.5-5
Hypokalaemia causes
GI loss (vomiting) Renal loss (hyperaldosteronism, excess cortisol, osmotic diuresis) Redistribution into cells (insulin, alkalosis) Rare (Tubular acidosis T1+2, Bartter's, Liddle's, Gitelman's)
Hyperkalaemia causes
Excessive intake (oral, parenteral, blood transfusion) Transcellular movement (acidosis, insulin shortage, tissue damage/catabolic state) Decreased excretion (ARF, CRF, Sprionolactone, Addison's NSAIDs, ACEi)
Adult maintenance fluid requirement
25-30ml/kg/day
Paediatric maintenance fluid requirement
1st 10 kg: 100ml/kg/day
2nd 10kg: 50ml/kg/day
Each kg after: 20ml/kg/day
Normal serum osmolality
275-295
Causes of HoNa w/ normal osmolality
Spurious, Drip arm sample, PseudoHoNa (hyperlipidaemia/paraproteinaemia) - everything normal except Na + Hx of DM or metabolic synd.
TURP syndrome
Hyponatraemia from water absorbed through damaged prostate
Differentiating Causes of Hypervolaemic HoNa
Urinary Na >20= Renal (ARF, CRF)
Urinary Na less than 20= Non renal (CCF, Cirrhosis)
Central pontine myelinosis
Pseudobulbar palsy, Paraparesis, Locked in syndrome due to Correcting HoNa too quickly
Increase Na by no more than 12mmol/L in 1st 24h
SIADH causes
Malignancy (SCLC, pancreas, prostate, lymphoma)
CNS disorders (meningoenceph., haem, abscess)
Resp (TB, pneumonia, abscess)
Drugs (opiates, SSRIs, Carbamazepine)
Addison’s bloods
HypoNa, HyperK, HypoGly, Urine Na >20
Bartter syndrome
Autosomal recessive
HypoK, Alkalosis + HoTN
Hypercalciuria + Nephrocalcinosis
Short SynACTHen
Cortisol measured at 0, ACTH given at 30mins + Cortisol measured at 60 mins
Final Cortisol less than 550= production defect
Long SynACTHen
1mg ACTH given and measure cortisol at 24h
>900= Secondary (Pituitary problem)
NB Secondary also has HypoK NOT HyperK
less than 900= Primary
OGTT for Acromegaly
75mg Glucose should decrease GH to 2 = Acromegaly
Schmidst’s syndrome
AI polyendocrine syndrome
Addison’s, HoTy + T1DM
Kallman’s syndrome
Hypogonadotrophic Hypogonadism
Low LH + FSH + Anosmia
Renal Tubular Acidosis
HypoK w/ Acidosis
T1 - Distal tubule (HypoCa)
T2 - Proximal Tubule (Fanconi -> HyperPhos -> Ricketts)
T3 - Both
T4 - Defect in adrenals (HyperK - deficiency of Aldosterone)
Drugs that causes nephrogenic DI
Lithium, Demeclocycline (used to Tx SIADH!)
Causes of conn’s
ABCD Adrenal Adenoma Bilateral nodular hyperplasia Ca of adrenals Defective gene (GRA)
Causes of Elevated anion gap Metabolic acidosis
MUDPILES Methanol Uraemia DKA Propylene glycol Isoniazid Lactic acidosis Ethylene glycol Salicylates
Causes of HoNa w/ high osmolality
Glucose, Mannitol, EtOH
Gilbert’s
Isolated unconj bili
Crigler-Najjar
Isolated unconj bili (more constant and severe than Gilbert’s)
Alcoholic liver disease LFTs
High AST> High ALT (AST:ALT>1) High GGT (chronic)
Hepatitis LFTs
High AST=High ALT
Cholestatic LFTs
High GGT + ALP then Increased AST, ALT + Bili (conj)
NAFLD LFTs
High AST + ALT (AST:ALT less than 1) + High GGT
Paracetamol poisoning LFTs
V high (>1000) AST + ALT > increase in GGT + ALP
Alcohol abuse LFTs
Isolated GGT increase
Dubin Johnson LFTs
Isolated conj bili
HCC LFTs
High AFP + any LFT picture (therefore unlikely to be answer unless AFP given!)
ALP
High ALP w/ High GGT confirms liver cause
Also increases w/ bone disease (e.g. Paget’s) + Pregnancy
Acute intermittent porphyria Ez Def
Autosomal Dominant
Porphobilinogen deaminase deficiency
Acute Intermittent Porphyria Sx
Abdo pain, seizures, N+V, muscle weakness, peripheral neuropathy after stress e.g. alcohol or infection
No cutaneous Sx
Porphyria Cutanea Tarda
Uroporphyrinogen decarboxylase deficiency
Sx: Vesicles on sun exposed sites
X linked sideroblastic Anaemia (Type of Porphyria)
ALA Synthase deficiency
Congenital erythropoietic porphyria
Uroporhyrinogen synthase deficiency
Hereditary coproporhyria
Copropophyrinogen oxidase deficiency
Variegate porphyria
Protopophyrinogen oxidase deficiency
Erythropoietic protoporphyria
Ferrochelatase deficiency
Anterior pituitary hormones
GH TSH ACTH Prolactin LH FSH
Posterior pituitary hormones
ADH (Vasopressin)
Oxytocin
Ca causing Bone Mets
BLT w/ a Kosher Pickle (prostate)
Dexamethasone Suppresion test
No suppression = Cushing’s syndrome (low ACTH- primary hypercortisolism) or Ectopic ACTH
Suppression after high dose= Cushing’s disease
Tx of Phaeo
Short acting alpha blocker then
Long acting alpha blocker then
Beta blocker then
Surgery
Phenytoin toxicity
HoTN, Heart block, Ventricular Arr., Ataxia, Nystagmus
Digoxin toxicity
Arr., Prolonged PR, Bradycardia, Xanthopsia
Lithium toxicity
D+V, Dysarthria + Coarse tremor
Gentamicin toxicity
Tinnitus, Deafness, Nystagmus, RF
Theophylline toxicity
N+D, taccy, Arr., Headache, Seizure
NB Toxicity precipitated by Erythromycin and Cipro
Procainamide toxicity
Rash, Fever, Agranulocytosis + DI-SLE
Methotrexate toxicity
Hepatotoxic, Ulcerative stomatitis, Leukopoenia, Pulmonary fibrosis
Carbamazepine toxicity
Headaches, Ataxia, Abdo pain, SIADH + aplastic An.
Cyclosporine toxicity
ARF
Ca Normal range
2.2-2.6
PTH actions
- Increase tubular Vit D 25(OH) -> Vit D 1,25(OH)2
- Mobilise Ca from bone (increase osteoclast activity)
- Increase renal Ca absorption + PO4 excretion
Calcitriol actions (1,25 (OH)2 Vit D)
Increase Ca and PO4 absorption from gut
Bone remodelling
Primary Hyperparathyroidism bloods
High Ca, Low PO4, High/N PTH, High/N ALP, N Vit D
Renal osteodystrophy (2o HyperPTy) bloods
Low Ca, High PO4, High PTH, High ALP
3o HyperPTy bloods
High Ca, Low PO4, High PTH, High/N ALP, N Vit D
NB Autonomous PTH secretion post renal transplant/dialysis
Hypoparathyroidism bloods
Low Ca, High PO4, Low PTH, N/low ALP, N Vit D
PseudoHoPTy bloods (Albright’s osteodystrophy)
Low Ca, High PO4, High PTH
Short stature + 4th+5th metacarpals, rounded facies
PseudoPseudoHoTy
Feats of Pseudo (short stature, rounded facies)
Normal Bloods
Sx of HyperCa
Stones (renal) Bones (pain) Groans (Psych) Moans (abdo pain) Polyuria Muscle weakness
Sx of HypoCa
Perioral parasthesiae Carpopedal spasm Trousseau's sign (BP cuff) Chovstek's sign Hypereflexia Tetany
Vitamin B1 (thiamine) deficiency
Sx: Wernicke’s (confusion, ataxia, ophthalmoplegia)
Wet beri beri
Test: RBC Transketolase
Vitamin B2 (riboflavin deficiency)
Sx: Stomatitis, oily skin rashes, anaemia
Test: RBC Glutathione
Vitamin B3 (niacin) deficiency
Sx: Pellagra, Casal’s necklace rash , Stomatitis, dementia, diarrhoea
Vitamin B5 (Pantothenic acid) deficiency
Sx: Chronic parasthesiae
Vitamin B7 (Biotin) deficiency
Sx: infertility and poor hair growth
Vitamin B9 (folate) deficiency
Sx: Megaloblastic anaemia
Test: Normal MMA
Vitamin B12 (Cobalamin) deficiency
Sx: Megaloblastic anaemia, glossitis, Peripheral neuropathy
Test: Raised MMA
Vitamin A (Retinol) deficiency
Sx: Dry skin, hair + cornea, Bitot’s spots on conjunctiva, night blindness
Vitamin B6 (Pyridoxine) deficiency
Sx: Sideroblastic anaemia + seborrhoeic dermatitis
Test: RBC AST
Commonly due to Isoniazid
Vitamin C (Ascorbic acid) deficiency
Sx: Bleeding in gums, skin and joints + bone weakness
Vitamin E (tocopherol) deficiency
Sx: Haemolytic anaemia + spinocerebellar neuropathy (ataxia + areflexia)
PKU
Phenylalanine hydroxylase deficiency
Sx: Fair haired, developmental delay between 6-12 months + musty smell
Homocysteinuria
Cystathionine synthetase deficiency
Sx: V fair skin + brittle hair, developmental delay + LD
Tx: Pyridoxine + low methionine diet
Galactosaemia
Gal-1-PUT deficiency
Sx: after milk ingestion - poor feed, vomiting, jaundice (conj) + hepatomegaly, hypoglycaemia + sepsis
SCAD
Sx: FTT, hypotonia, metabolic acidosis, hyperglycaemia
Von Gierke’s
GSD T1
Hypoglycaemia in infancy
Hepatomegaly +/- splenomegaly
Pompe
GSD - lysosomal alpha glucosidase deficiency
Cori’s
GSD - Amylo 1,6 glucosidase deficiency
McArdle’s
GSD - Phosphorylase deficiency
Maple syrup urine disease
Impaired metabolism of leucine, isoleucine + valine causes encephalopathy
Sx: Lethargy, poor feeding, hypotonia
Sweet odour + Sweaty feet
Fabry’s disease
LSD - alpha galactosidase deficiency
Sx: developmental delay and dysmorphia
“Cherry red spot”
Peroxisomal disorders
Disordered beta oxidation of VLCFA
Sx: Seizures, dysmorphic, severe hypotonia + jaundice
Retinopathy + large fontanelle
Gout exacerbating factors
Aspirin (other NSAIDs Tx) Chemotherapy Alcohol Psoriasis Thiazides
Glasgow pancreatitis score
PANCREAS PaO2 less than 9 Age >55 Neutrophilia WCC>15 Calcium less than 2 Renal failure urea>16 Ezs - LDH >600 or AST >200 Albumin less than 32 Sugar >10
Barth Mitochondrial disorder
Presents at birth w/ Cardiomyopathy, Neutropoenia, Myopathy
MELAS Mitochondrial disorder
Presents age 5-15 w/
Mitochondrial Encephalopathy
Lactic acidosis
Stroke-like episodes
Kearns Sayre Mitochondrial disorder
Presents age 12-30 w/ CPEO Retinopathy Deafness Ataxia
Diabetes Dx
One test + Sx or 2 tests: Fasting glucose >7 OGTT >11.1 Random glucose >11.1 HbA1c >48 (6.5%)
Impaired glucose tolerance Dx
Fasting glucose 6.1-6.9
Random glucose or OGTT 7.8-11.1