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Meded Path Lectures > Chem Path 1 > Flashcards

Chem Path 1 Flashcards

1
Q

Osmolality

A

mOsm/kg
More accurate, machine measured

2(Na+K) + Glucose + Urea
275-295 = range

Sodium = largest contributor

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2
Q

Osmolarity

A

mOsm/L

More practical, calculated

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3
Q

Osmolar gap

A

Measured osmolality - calculated osmolality

> 10

Caused by other solutes, ie alcohols, lipids, proteins etc

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4
Q

Sodium Regulation

A

ANP released by atrial stretch, occurs when blood volume is higher
ANP reduces release of aldosterone, ADH and renin = lower BP

High osmolality = ADH release = water reabsorption = reduced sodium concentration

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5
Q

Assessing Hyponatraemia

A
  1. Check Osmolality, Pseudohyponatraemia = low sodium, normal/high osmolality
  2. Assess fluid status
  3. Check Urinary Sodium
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6
Q

Hypovolaemic Hyponatraemia management

A

Treat cause

IV .9% NaCl or slow hypertonic 3% NaCl

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7
Q

Extra renal hypovolaemic hyponatraemia causes

A

Vomiting, Diarrhoea, Burns

<20mmol/L urine sodium

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8
Q

Renal hypovolaemic Hyponatraemia causes

A

Renal Disease, Diuretics, Cerebral salt wasting

>20mmol/L urine sodium

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9
Q

Assessing Hypovolaemic Hyponatraemia

A
  1. Check urinary Sodium (<20 = extra renal loss, >20 = renal loss)
    Low body water, appropriately high ADH
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10
Q

Assessing Hypervolaemic Hyponatraemia

A
  1. Check urinary Sodium (<20 = extra renal loss, >20 = renal loss)
    High body water, low arterial volume
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11
Q

Extra-renal hypervolaemic hyponatraemia causes

A

Reduced cardiac output -> CCF
Increased arterial vasodilation -> Cirrhosis
Nephrotic Syndrome

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12
Q

Renal Hypervolaemic Hyponatraemia causes

A

CKD

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13
Q

Hypervolaemic Hyponatraemia management

A

Treat cause

Fluid restrict

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14
Q

Assessing Euvolaemia Hyponatraemia

A
  1. Check urinary Sodium (<20 = extra renal loss, >20 = renal loss)
    More body water relative to sodium
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15
Q

Renal euvolaemic hyponatraemia causes

A

Hypothyroidism
Adrenal Insufficiency
SIADH

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16
Q

Extra-renal euvolaemic hyponatraemia causes

A

Psychogenic Polydipsia

Tea and toast diet in elderly

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17
Q

Euvolaemic hyponatraemia management

A

Treat cause

Fluid restrict

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18
Q

Resistant SIADH management

A

Demeclocycline

Tolvaptan

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19
Q

Causes of SIADH

A

Brain: Stroke, Tumour

Lung: Tumour, small cell paraneoplastic syndrome

Pills: PPI, SSRI, carbamazepine

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20
Q

SIADH diagnosis

A

diagnosis of exclusion

Check TFTs/Cortisol

Need euvolaemic hyponatraemia with low osmolality, high urinary sodium and no endo cause

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21
Q

Assessing Hypernatraemia

A

= high osmolality

  1. Assess volume status
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22
Q

Hypervolaemic Hypernatraemia

A

Hypertonic 3% NaCl

Hyperaldosteronism (Conn’s if adenoma, Cushing’s)

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23
Q

Hypovolaemic Hypernatraemia

A

Osmotic Diuresis
Diarrhoea
Burns

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24
Q

Euvolaemic Hypernatraemia

A

Diabetes Insipidus

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25
Q

Hypernatraemia Management

A

Water intake

Slow IV 5% dextrose (1L/6h) -> guide this. by urine output and serial plasma sodium measurements

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26
Q

Diabetes Insipidus types

A

Central (no ADH):
Pituitary surgery, irradiation, tumour, trauma

Nephrogenic (ADH resistance)
Low K, High Ca, Lithium, demeclocycline (tetracycline antibiotic)

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27
Q

Central DI management

A

Desmopressin, ADH analogue

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28
Q

Nephrogenic DI management

A

Thiazide Diuretics,

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29
Q

Diabetes Insipidus diagnosis

A

Diagnosis of exclusion
Normal Glucose (exclude diabetes)
Normal Potassium/Calcium (exclude electrolyte abnormalities)
Plasma and urine osmolality (check for other hypernatraemia causes)

Water deprivation test

30
Q

Water Deprivation Test

A

Checks for DI Type
Restrict Water, give desmopressin

Concentrated urine = normal/primary polydipsia as ADH works

Concentrated post desmopressin = central as no adh production

Dilute post desmopressin = nephrogenic as can’t respond to ADH

Raised osmolality, urine:plasma <2:1 (if ratio is higher than 2:1, DI is excluded

31
Q

Hypokalaemia features

A

Muscle weakness, cramps, hypotonia

Metabolic Alkalosis

ECG -> Inverted T, Big U, Prolonged PR, ST depression

32
Q

Hypokalaemia causes

A

Loss (D/V/stoma, renal loss (diuretics, conns, congenital syndromes))

Increased cellular influx (insulin, beta agonists, refeeding syndrome, metabolic alkalosis)

Decreased intake (rare)

33
Q

Hypokalaemia and metabolic acidosis?

A

Renal tubular acidosis, treated DKA

34
Q

Hypokalaemia investigation

A

Check hypomagnesium (correct if low)

Aldosterone:Renin Ratio if also high BP

35
Q

Hypokalaemia management

A

Depends on severity

Mild (2.5-3.5) Oral Sando-K

Severe (less than 2.5) 10mmol/hour IV KCl and ECG monitoring

Daily U&Es

36
Q

Hyperkalaemia ECG

A 
Tall tented T
Small P
Wide QRS
Prolonged PR
Sine wave if severe
37
Q

Hyperkalaemia causes

A

Artefact (Haemolysed sample)

Iatrogenic (If bleeding and have transfusion, or excessive potassium replacement )

Less Excretion (Renal disease, aldosterone deficiency, potassium sparing diuretics/ACEi/ARBs)

Increased cellular release (Metabolic Acidosis, Tissue breakdown ie rhabdomyolysis)

38
Q

Hyperkalaemia Investigation

A

Check renal function - U&Es, Creatinine, GFR

Check Endo -> Cortisol, short SynACTHen

Creatine Kinase, check tissue breakdown in elderly fall

39
Q

Hyperkalaemia management

A

Treat if ECG changes or >6.5 on multiple samples

IV Calcium Gluconate

IV Insulin with Dextrose

???Salbutamol, Potassium Binders, Dialysis

40
Q

Calcium in the body

A

99% Bone

1% Serum, half is free, 40% albumin, 10% citrate/phosphate

41
Q

Calcium Homeostasis

A

Parathyroid Hormone leads to Increased serum calcium and decreased serum phosphate

Calcitonin directly opposes parathyroid hormone.

42
Q

What does parathyroid hormone do?

A

Increased Ca reabsorption in gut
Increased Bone resorption by osteoclasts
Less PO4 reabsorption at PCT, more Ca at DCT

Calcitriol (active vit D) helps

43
Q

Hypocalcaemia Signs

A

Paraesthesia, Arrythmia (Long QT), Tetany (trousseau’s sign), Spasm (Chvostek’s Sign)

44
Q

Causes of Hypocalcaemia

A

Hypoparathyroidism -> DiGeorge (Primary), Thyroidectomy (Secondary), Low Magnesium

Vit. D Deficiency

45
Q

Hypocalcaemia Investigations

A

ECG
Mg, Phosphate, PTH, ALP
DEXA scan if Hx for osteoporosis

46
Q

Hypocalcaemia Management

A

Mild (>1.9, no sx), Oral Ca/Vit D

Severe (<1.9, Sx), IV Ca Gluconate

47
Q

Hypercalcaemia Signs

A 
Stones
Bone pain
Abdo Pain, constipation 
Polyuria/dipsia
Depression/Psychiatric changes
48
Q

Hypercalcaemia Causes with low pth

A

Low Pth? Malignancy (Metastatic bone, breast lung, prostate, MM), High t4, Hypoadrenalism, sarcoidosis, thiazides, too much Vit D

49
Q

Hypercalcaemia causes with high pth

A

Primary/Tertiary Hyperparathyroidism
Primary = Parathyroid adenoma, MEN1/2a
Tertiary = Late stage CKD = Autonomous PTH production

50
Q

Investigations in Hypercalcaemia

A

Myeloma Screen, TFTs, Cortisol levels

51
Q

Hypercalcaemia management

A

Acute -> IV .9% NaCl with diuretics if risk of overload

Medical -> Bisphosphonates (for malignancy), Cinacalcet

Surgical -> Parathyroidectomy if parathyroid adenoma

52
Q

Paget’s

A

Abnormal Bone remodelling

Isolated raised ALP

53
Q

Osteoporosis

A

Normal Bloods

54
Q

Vit D Deficiency bloods

A

Raised PTH, ALP

Low Ca, PO4, Vit D

55
Q

Secondary Hyperparathyroidism

A

CKD = low Ca = High PTH

56
Q

Primary Hyperparathyroidism cause

A

Parathyroid Adenoma most commonly

57
Q

Raised ALP mechanism

A

Osteoblast Activation

58
Q

Cancers that metastasise to the bones

A

Prostate>Breast>Lung

59
Q

Anion Gap

A

Used to distinguish between equivocal blood gases (ie. compensated resp alk. and mixed resp alk and met acid)

Are there other things in the blood that may affect pH?

(Na+K)-(HCO3+Cl)
14-18

60
Q

Markers of liver function

A

Clotting (PT/INR)
Albumin
Bilirubin

61
Q

Markers of liver damage

A 
Bilirubin 
Alanine Transaminase
Aspartate Aminotransferase
Alkaline Phosphatase
Gamma Glutamyl Transferase
62
Q

Prehepatic Jaundice

A

Haemolytic Anaemia
Ineffective Erythropoeisis

No conjugated Bilirubin
No Urine bilirubin

63
Q

Hepatic Jaunidce

A

Hepatocellular Dysfunction/Impaired Conjugation, Impaired Bilirubin Uptake

64
Q

Post-Hepatic Jaundice

A

Stones
Pancreatic Cancer

Dark urine (raised urobilinogen), pale stool (low stercobilinogen)

65
Q

Aspartate Aminotransferase : Alanine Transaminase ratio

A

> 2:1 = Alcoholic Hepatitis

<1:1 = Viral Hepatitis

ALT/AST in 1000s = Acute viral/ Ischaemic/ Toxins (ie. Paracetamol overdose

66
Q

Causes of raised unconjugated bilirubin

A

Increased Haemolysis (Spherocytosis, haemoglobinuria)

Impaired Hepatic Uptake (Drugs, contrast, rifampicin)

Impaired Conjugation (Gilbert’s Syndrome, Crigler-Najjar Syndrome)

67
Q

Causes of raised conjugated bilirubin

A

Hepatocellular Dysfunction

Decreased hepatic excretion

68
Q

What is the enzyme deficiency in Gilbert’s?

A

UDP-Glucoronyl Transferase

69
Q

Sources of raised ALP

A 
Paget's 
Placenta
GI
Kidney 
Prostate
70
Q

Isolated raised ALP

A

Pregnancy
Growth spurt in childhood
Pathological

71
Q

Isolated GGT and ALP

A

Cholestasis, gallstones, co-amoxiclav, OCP, Sulphonylurea, Alcoholic Hepatitis

72
Q

What is the best marker of liver function in acute liver injury?

A

Prothrombin Time

Meded Path Lectures (15 decks)

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