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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
Hypernatraemia Management
Water intake | Slow IV 5% dextrose (1L/6h) -> guide this. by urine output and serial plasma sodium measurements
26
Diabetes Insipidus types
Central (no ADH): Pituitary surgery, irradiation, tumour, trauma Nephrogenic (ADH resistance) Low K, High Ca, Lithium, demeclocycline (tetracycline antibiotic)
27
Central DI management
Desmopressin, ADH analogue
28
Nephrogenic DI management
Thiazide Diuretics,
29
Diabetes Insipidus diagnosis
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
Water Deprivation Test
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
Hypokalaemia features
Muscle weakness, cramps, hypotonia Metabolic Alkalosis ECG -> Inverted T, Big U, Prolonged PR, ST depression
32
Hypokalaemia causes
Loss (D/V/stoma, renal loss (diuretics, conns, congenital syndromes)) Increased cellular influx (insulin, beta agonists, refeeding syndrome, metabolic alkalosis) Decreased intake (rare)
33
Hypokalaemia and metabolic acidosis?
Renal tubular acidosis, treated DKA
34
Hypokalaemia investigation
Check hypomagnesium (correct if low) Aldosterone:Renin Ratio if also high BP
35
Hypokalaemia management
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
Hyperkalaemia ECG
``` Tall tented T Small P Wide QRS Prolonged PR Sine wave if severe ```
37
Hyperkalaemia causes
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
Hyperkalaemia Investigation
Check renal function - U&Es, Creatinine, GFR Check Endo -> Cortisol, short SynACTHen Creatine Kinase, check tissue breakdown in elderly fall
39
Hyperkalaemia management
Treat if ECG changes or >6.5 on multiple samples IV Calcium Gluconate IV Insulin with Dextrose ???Salbutamol, Potassium Binders, Dialysis
40
Calcium in the body
99% Bone | 1% Serum, half is free, 40% albumin, 10% citrate/phosphate
41
Calcium Homeostasis
Parathyroid Hormone leads to Increased serum calcium and decreased serum phosphate Calcitonin directly opposes parathyroid hormone.
42
What does parathyroid hormone do?
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
Hypocalcaemia Signs
Paraesthesia, Arrythmia (Long QT), Tetany (trousseau's sign), Spasm (Chvostek's Sign)
44
Causes of Hypocalcaemia
Hypoparathyroidism -> DiGeorge (Primary), Thyroidectomy (Secondary), Low Magnesium Vit. D Deficiency
45
Hypocalcaemia Investigations
ECG Mg, Phosphate, PTH, ALP DEXA scan if Hx for osteoporosis
46
Hypocalcaemia Management
Mild (>1.9, no sx), Oral Ca/Vit D Severe (<1.9, Sx), IV Ca Gluconate
47
Hypercalcaemia Signs
``` Stones Bone pain Abdo Pain, constipation Polyuria/dipsia Depression/Psychiatric changes ```
48
Hypercalcaemia Causes with low pth
Low Pth? Malignancy (Metastatic bone, breast lung, prostate, MM), High t4, Hypoadrenalism, sarcoidosis, thiazides, too much Vit D
49
Hypercalcaemia causes with high pth
Primary/Tertiary Hyperparathyroidism Primary = Parathyroid adenoma, MEN1/2a Tertiary = Late stage CKD = Autonomous PTH production
50
Investigations in Hypercalcaemia
Myeloma Screen, TFTs, Cortisol levels
51
Hypercalcaemia management
Acute -> IV .9% NaCl with diuretics if risk of overload Medical -> Bisphosphonates (for malignancy), Cinacalcet Surgical -> Parathyroidectomy if parathyroid adenoma
52
Paget's
Abnormal Bone remodelling | Isolated raised ALP
53
Osteoporosis
Normal Bloods
54
Vit D Deficiency bloods
Raised PTH, ALP | Low Ca, PO4, Vit D
55
Secondary Hyperparathyroidism
CKD = low Ca = High PTH
56
Primary Hyperparathyroidism cause
Parathyroid Adenoma most commonly
57
Raised ALP mechanism
Osteoblast Activation
58
Cancers that metastasise to the bones
Prostate>Breast>Lung
59
Anion Gap
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
Markers of liver function
Clotting (PT/INR) Albumin Bilirubin
61
Markers of liver damage
``` Bilirubin Alanine Transaminase Aspartate Aminotransferase Alkaline Phosphatase Gamma Glutamyl Transferase ```
62
Prehepatic Jaundice
Haemolytic Anaemia Ineffective Erythropoeisis No conjugated Bilirubin No Urine bilirubin
63
Hepatic Jaunidce
Hepatocellular Dysfunction/Impaired Conjugation, Impaired Bilirubin Uptake
64
Post-Hepatic Jaundice
Stones Pancreatic Cancer Dark urine (raised urobilinogen), pale stool (low stercobilinogen)
65
Aspartate Aminotransferase : Alanine Transaminase ratio
>2:1 = Alcoholic Hepatitis <1:1 = Viral Hepatitis ALT/AST in 1000s = Acute viral/ Ischaemic/ Toxins (ie. Paracetamol overdose
66
Causes of raised unconjugated bilirubin
Increased Haemolysis (Spherocytosis, haemoglobinuria) Impaired Hepatic Uptake (Drugs, contrast, rifampicin) Impaired Conjugation (Gilbert's Syndrome, Crigler-Najjar Syndrome)
67
Causes of raised conjugated bilirubin
Hepatocellular Dysfunction | Decreased hepatic excretion
68
What is the enzyme deficiency in Gilbert's?
UDP-Glucoronyl Transferase
69
Sources of raised ALP
``` Paget's Placenta GI Kidney Prostate ```
70
Isolated raised ALP
Pregnancy Growth spurt in childhood Pathological
71
Isolated GGT and ALP
Cholestasis, gallstones, co-amoxiclav, OCP, Sulphonylurea, Alcoholic Hepatitis
72
What is the best marker of liver function in acute liver injury?
Prothrombin Time

Meded Path Lectures (15 decks)

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