Biochemistry

Question 1

Sodium follows water everywhere. True/False?

Answer 1

False

Water follows sodium!(WafS)

Question 2

Concentration of Na inside the cell is more than concentration of Na outside the cell. True/False?

Answer 2

False

Concn of Na outside cell is greater than inside

Question 3

What does mineralocorticoid activity refer to?

Answer 3

Sodium retention in exchange for potassium and/or hydrogen ions

Question 4

What is the main steroid in the body with mineralocorticoid activity?

Answer 4

Aldosterone

Question 5

Excess mineralocorticoid activity causes what?

Answer 5

Sodium retention

Question 6

What effect does sodium loss have upon water?

Answer 6

Sodium loss means water loss (water follows sodium!)

Question 7

Outline what happens in terms of sodium and water when blood pressure drops

Answer 7

Decreased blood pressure causes sodium + water retention in order to compensate and bring blood pressure up

Question 8

Which hormone controls water reabsorption?

Answer 8

ADH

Question 9

What effect does ADH have on water reabsorption and thus urine output?

Answer 9

Causes increased water reabsorption (anti-diuresis), producing low-volume concentrated urine

Question 10

Concentrated/small volume urine has a high omolality. True/False?

Answer 10

True

Question 11

What are the main causes of decreased sodium levels?

Answer 11

Too much water

Too little sodium

Question 12

What are the main causes of increased sodium levels?

Answer 12

Too little water

Too much sodium

Question 13

Decreased sodium levels can be due to too much water. How can this arise?

Answer 13

SIADH (inappropriate ADH secretion)

Compulsive water drinking

Question 14

Decreased sodium levels can be due to too little sodium. How can this arise?

Answer 14

Sodium loss (renal insufficiency, gut fistulae)
Decreased sodium intake (rare)

Question 15

Increased sodium levels can be due to too little water. How can this arise?

Answer 15

Water loss (diabetes insipidus)
Decreased water intake

Question 16

Increased sodium levels can be due to too much sodium. How can this arise?

Answer 16

IV medication
Drowning in sea
High-salt feeds

Question 17

Outline pathogenesis of Addison’s disease

Answer 17

Adrenal insufficiency;can’t make enough aldosterone;can’t retain enough sodium;lose sodium + water;low ECF volume, so patient is dehydrated + dizzy

Question 18

What is the main osmotic stimulus for ADH release?

Answer 18

High sodium (high osmolality) causes increased ADH

Question 19

Does hypovolaemia cause increased or decreased ADH release?

Answer 19

Increased ADH release (to compensate for loss of fluid)

Question 20

Outline the main treatment for too much sodium

Answer 20

Loop diuretic

Question 21

Outline the treatment for SIADH

Answer 21

Fluid restrict to 0.5l

Sodium should rise

Question 22

Outline the treatment for diabetes insipidus

Answer 22

Desmopressin (synthetic ADH)

Question 23

Outline the treatment for too little sodium

Answer 23

Sodium supplement

Question 24

List features of Addison’s disease

Answer 24

Skin pigmentation (high ACTH)
Dizziness
Low BP
Hyponatraemia
Hyperkalaemia

Question 25

State the diagnostic test for adrenal insufficiency

Answer 25

Short synacthen test

Question 26

What are the two types of adrenal insufficiency?

Answer 26

Primary e.g. Addison's | Secondary e.g. long-term use of CCS

Question 27

List ECG changes found in hyperkalaemia

Answer 27

Tall tented T waves | Broad QRS

Question 28

Give symptoms of hyperkalaemia

Answer 28

Muscle weakness | Paraesthesia

Question 29

List causes of hyperkalaemia

Answer 29

``` Reduced excretion (renal failure, hypoaldosteronism) Redistribution (metabolic acidosis, rhabdomyolysis, insulin deficiency) Increased intake (potassium salts) ```

Question 30

List treatment options for hyperkalaemia

Answer 30

Calcium gluconate Insulin 50% dextrose Dialysis

Question 31

What is pseudohyperkalaemia?

Answer 31

Increase in concentration of potassium due to its movement out of cells in a haemolysed blood sample

Question 32

List symptoms of hypercalcaemia

Answer 32

``` Confusion Abdominal pain Renal stones Polyuria, polydipsia Constipation ```

Question 33

List the common causes of hypercalcaemia

Answer 33

Primary hyperparathyroidism Hypercalcaemia of malignancy Thiazide diuretic therapy Sarcoidosis

Question 34

Outline treatment for hypercalcaemia

Answer 34

IV fluids Biphosphonates Treat cause e.g. surgery

Question 35

What is familial benign hypercalcaemia?

Answer 35

High calcium is sensed by the parathyroid as normal, therefore the patient has normal PTH and high calcium

Question 36

By what mechanisms, does the kidney regulate blood volume?

Answer 36

Renal excretion of sodium Renal excretion of water via RAAS system

Question 37

List ways in which hyponatraemia is assessed

Answer 37

``` Serum sodium (plasma osmolality) Urine sodium (volume status) ```

Question 38

How do you distinguish between hyponatraemia and pseudohyponatraemia?

Answer 38

Measure serum osmolality (normal in pseudo)

Question 39

How do you distinguish between central and nephrogenic diabetes insipidus?

Answer 39

DDAVP, synthetic analogue of ADH Central is due to a lack of ADH Nephrogenic is due to reduced response to ADH

Question 40

What type of lung cancer is most associated with the production of ADH?

Answer 40

Small cell carcinoma

Question 41

What type of lung cancer is most associated with hypercalcaemia?

Answer 41

Squamous cell carcinoma

Question 42

Patients with adrenal insufficiency are less able to retain infused saline (sodium) than normal subjects. True/ False?

Answer 42

True | Addison's patients are unable to hold onto sodium

Question 43

How do you distinguish between primary and secondary adrenal insufficiency?

Answer 43

Measure ACTH | Reduced in secondary insufficiency

Question 44

List the role of PTH

Answer 44

Bone resorption (increase calcium) Activate vitamin D in kidneys (increase calcium) Increase GI calcium absorption

Question 45

Why is rehydration so important in hypercalcaemia patients?

Answer 45

It interferes with proximal tubular reabsorption of sodium and so causes loss of sodium and water patients are usually dehydrated

Question 46

List drugs that are at risk of causing hyperkalaemia

Answer 46

Potassium-sparing diuretics (eg, spironolactone) NSAIDs ACE inhibitors. Angiotensin-receptor blockers (ARBs)

Question 47

Give two side effects of rhabdomyolysis

Answer 47

Acute renal failure | Disseminated intravascular coagulation

Question 48

What gross findings suggest contamination with potassium EDTA, the anticoagulant used in the purple top (FBC) bottle?

Answer 48

Gross hypocalcaemia | Gross hyperkalaemia

Question 49

What is meant by a high vs low urine osmolality?

Answer 49

``` High = concentrated urine Low = dilute urine ```

Question 50

How do you test for secondary adrenal insufficiency?

Answer 50

Short synacthen test | It would show a suppressed ACTH