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House Clinical Pathology > Calcium, Phosphate , Magnesium > Flashcards

Calcium, Phosphate , Magnesium Flashcards

1
Q

Disorders of calcium metabolism are (common or rare?) in clinical practice and they are closely associated with disorders of _______ and ______ metabolism

A

Common

phosphate and magnesium

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2
Q

Distribution of Body Calcium

The total body calcium depend on the amount _________ and the amount _________

A

absorbed from the diet

lost from the body

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3
Q

Distribution of Body Calcium

About ______% of Calcium in the body is part of bone.

The remaining __% is mostly in the _______ and ______

A

99

1; blood and ECF

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4
Q

Distribution of Body Calcium

The extra-osseous fraction is very important because of its effect in ____________ and ___________

A

neuromuscular excitability and cardiac muscle contraction.

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5
Q

Distribution of Body Calcium

The reference interval for plasma total calcium concentration is _______-_______ mmol/L

A

2.15-2.55

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6
Q

Calcium in blood is distributed among several forms.

T/F

A

T

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7
Q

Distribution of Body Calcium

About 45% circulates as _________

40% is ________________, mostly ______

15% is ______________ such as _________

A

free Calcium ions

bound to protein, mostly albumin

bound to anions, such as HCO3 , citrate, PO4 , and lactate.

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8
Q

Distribution of Body Calcium

About ____% circulates as free Calcium ions

_____% is bound to protein, mostly albumin

____% is bound to anions, such as HCO3 , citrate, PO4 , and lactate.

A

45

40

15

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9
Q

free Calcium ions

referred to as ______ Ca2

A

ionized

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10
Q

Distribution of Body Calcium

The free ionized calcium is the physiologically (active or inactive?) fraction.

A

Active

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11
Q

Distribution of Body Calcium

The albumin bound fraction is known as the physiologically (active or inactive?) fraction.

A

Inactive

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12
Q

Distribution of Body Calcium

The ____________ calcium functions in neuromuscular excitability and cardiac muscle contraction
M

A

free ionized

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13
Q

Distribution of Body Calcium

The reference interval for plasma free ionised calcium concentration is ______-____ mmol/L

A

1.1-1.4

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14
Q

Control of Plasma Calcium
Factors involved in the control of calcium include:

_______ supply of calcium
________
Normal functioning _______
________ glands
Normal functioning ________.

A

Dietary

Vitamin D.

intestines

Parathyroid

kidneys

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15
Q

Control of Plasma Calcium
Parathyroid Hormone

Secreted from the ________ gland

PTH is a _____ chain polypeptide containing _____ residues, the ____ N terminal amino acid largely determines its biological activity.

A

parathyroid

single; 84; 34

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16
Q

Control of Plasma Calcium

Actions of PTH
1. It increases the plasma concentration of ____________ by stimulating _______ bone __________

  1. On the kidneys, it causes decreased tubular re- absorption of ______ causing ____ and decreased ______ levels while it increases plasma ______ by increasing tubular reabsorption of ________.
A

calcium and phosphate; osteoclastic; resorption

phosphate; phosphaturia; phosphate

calcium; calcium

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17
Q

Control of Plasma Calcium
The control of PTH depends on:

  1. Plasma _________ concentration
  2. _____cellular ______ concentration
A

free ionized calcium

Extra; magnesium

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18
Q

plasma PTH conc. is _____eased by severe chronic hypomagnesaemia

A

decr

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19
Q

Control of Plasma Calcium

•Parathyroid Hormone Related Protein

This is a peptide hormone that has a similar ________ with PTH at the biologically ________

It is actively increased in certain ______ causing humoral __________ of malignancy

A

amino acid sequence

active end.

tumours

hypercalcaemia

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20
Q

Control of Plasma Calcium

Calcitonin

Calcitonin, which originates in the ______ cells of the ______ gland, is secreted when the concentration of Calcium in blood ____eases.

A

medullary; thyroid; incr

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21
Q

Control of Plasma Calcium

Calcitonin exerts its calcium lowering effect by _________________________

A

inhibiting the actions of both PTH and vitamin D.

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22
Q

Calcitonin is however secreted during normal regulation of the ionized Ca2 concentration in blood

T/F

.

A

F

not

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23
Q

Calcitonin is secreted in response to a _____calcemic stimulus

A

hyper

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24
Q

Control of Plasma Calcium

vitamin D –

Sources of vitamin D

Vitamin D3, aka ________, is obtained from the _________ or _______

A

cholecalciferol

diet or exposure of skin to sunlight

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25
Q

Control of Plasma Calcium

Vitamin D

____calciferol (vitamin D2) obtained from _____ in the _____

_____calciferol (vitamin D3) formed in the _____ by the action of ___________ on _____________

A

Ergo; plants; diet

Chole; skin

ultra violet light on 7 dehydrocholesterol

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26
Q

Control of Plasma Calcium

Metabolism of Vitamin D

Vitamin D is transported in blood bound to specific carrier protein – __________________

In the ____, cholecalciferol is hydroxylated to ——————————- by the enzyme __________.

A

the vitamin D binding protein.

liver

25 hydroxycholecalciferol (25OHD3)

25- hydroxylase

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27
Q

Control of Plasma Calcium

_______________ is the main circulatory form and store of the vitamin.

A

25 hydroxycholecalciferol (25OHD3)

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28
Q

Control of Plasma Calcium

Vitamin D metabolism

In the _____ renal tubular cells of the kidney, _______ undergoes a second hydroxylation to form the active metabolite - __________________

A

proximal

25OHD3

1,25 dihydroxycholecalciferol

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29
Q

Control of Plasma Calcium

Vitamin D metabolism

The production of 1,25(OH)2D3 by ________________ may be stimulated by (low or high?) plasma phosphate concentration and ____eased PTH concentration

A

1-alpha - hydroxylase

Low

incr

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30
Q

Control of Plasma Calcium

Vitamin D metabolism

The 1-alpha -hydroxylase activity is inhibited by ____phosphataemia and (low or high?) levels of free ionized calcium

A

hyper

High

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31
Q

Control of Plasma Calcium

Vitamin D metabolism

The synthesis of the hormone 1,25 (OH)2 Vit D3 decreases in ____ disease and can lead to ____calcaemia.

A

renal

hypo

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32
Q

Control of Plasma Calcium

Actions of 1,25(OH)2 Vitamin D3

It Increases ____________ absorption by ___________ cells

A

calcium and phosphate

intestinal mucosal

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33
Q

Control of Plasma Calcium

Actions of 1,25(OH)2 Vitamin D3

It acts synergistically with _____ to stimulate ________ activity and release ______ from _____

A

PTH; osteoclastic

calcium from bone.

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34
Q

The action of PTH on bone is impaired in the absence of 1,25(OH)2 Vitamin D3.

T/F

A

T

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35
Q

PTH enhances _________ activity and therefore stimulation 1,25- (OH)2 Vit. D3 synthesis.

A

1- hydroxylase

36
Q

Disorders of Calcium Metabolism: Hypercalcaemia

Hypercalcaemia has clinical consequences

Renal effects – renal damage, _____uria, renal calculi due to precipitation of ________

______kalemia

Neuromuscular effects – it (depresses or enhances?) neuromuscular excitability leading to ____tonia.

A

poly; calcium phosphate stones.

Hypo; depresses

hypo

37
Q

calcium directly inhibits potassium reabsorption from the tubular lumen.

T/F

A

T

38
Q

Disorders of Calcium Metabolism

Hypercalcemia

CNS effects –______, anorexia, nausea and vomiting.

GIT effect – _________, constipation and abdominal pain.

A

depression

peptic ulceration

39
Q

Disorders of Calcium Metabolism

Hypercalcemia

Cardiac effect – ECG changes with _________ of the Q-T interval and ________ of the T waves.

At Ca >3.5mmoles/L, there is increased risk of sudden ________ or _________

A

shortening

broadening

cardiac arrest or ventricular arrhythmias.

40
Q

Severe hypercalamia should be treated as a medical emergency.

T/F

A

T

41
Q

Causes of Hypercalcaemia

_______ diuretics

____ metastasis
___________ abnormalities
(Low or High?) bone turnover
(Low or High?) levels of vitamin D

A

Thiazide

Bony

Parathyroid hormone

High

High

42
Q

Causes of Hypercalcaemia

Thiazide diuretics (________________)

Bony metastasis- from breast, lung, prostate, kidney and thyroid carcinomas.

Parathyroid hormone abnormalities- ————- and ______

High bone turnover-__________, prolonged _________

A

reduced calcium excretion

primary and tertiary hyperparathyroidism

thyrotoxicosis; immobilization

43
Q

Causes of Hypercalcaemia

Primary Hyperparathyroidism

This is caused by ________________________ causing hypercalcaemia.

A

inappropriate secretion of PTH by the PTH glands

44
Q

Causes of Hypercalcaemia

It may be due to an ________, ________ or __________ of the parathyroid glands.

A

adenoma

hyperplasia or carcinoma

45
Q

Causes of Hypercalcaemia

Tertiary Hyperparathyroidism

This may occur if the parathyroid glands have been subjected to ________________ by ______________ which has been subsequently corrected.

A

long standing and sustained positive feedback

hypocalcaemia of secondary hyperparathyroidism

46
Q

Causes of Hypercalcaemia

Tertiary Hyperparathyroidism

The parathyroid glands ________, PTH secretion becomes _________ and not suppressed by ________ of ________

A

hypertrophy

partly autonomous

negative feedback of hypercalcaemia.

47
Q

Causes of Hypercalcaemia

Hypercalcaemia of Malignancy
a)_________ of the _________
b)________________ of Malignancy

A

Malignant Disease of the Bone

Humoral Hypercalcaemia

48
Q

Causes of Hypercalcaemia

Hypercalcaemia of Malignancy

a)Malignant Disease of the Bone

———- from tumours of the breast, lungs, prostate, kidney and thyroid cause hypercalcaemia.

Plasma ______ is also high from bone break down due to local action of malignant deposits

The malignant deposits stimulate a local _______ reaction and hence plasma _________ activity is raised.

A

Bony metastasis

phosphate

osteoblastic

alkaline phosphatase

49
Q

Causes of Hypercalcaemia

Hypercalcaemia of Malignancy

B) Humoral Hypercalcaemia of Malignancy

Some malignant tumors secret ________.
This secretion is not subject to _________ by high plasma free ionized calcium concentration.

A

PTHRP

normal feedback control

50
Q

Drugs/Medication

Various medication can cause hypercalcaemia such as _______ which decreases renal calcium excretion.

Others include _______ and ________

Vitamin ___ Excess

___________ treatment of hypocalcaemia.

A

thiazides

Lithium and Vitamin A.

D

Over enthusiastic

51
Q

Causes of Hypercalcaemia

Sarcoidosis

The granulomatous tissue in sarcoidosis may _________________ , causing increased calcium absorption from the GIT.

_____________ and _________ may also produce the same effect.

A

synthesize 1,25(OH)2 cholecalciferol

Histoplasmosis and leprosy

52
Q

Treatment of Severe Hypercalcaemia

Re-________
Bisphosphonates e.g. ________ (Ca binders)
________ especially in Vit. D intoxication and sarcoidosis
Calcitonin

A

hydration

pamidronate

Steroids

53
Q

Hypocalcaemia Clinical Effects

_______,_______ spasm, generalized ________

__________ Sign
__________ sign

A

Tetany, carpo-pedal

seizure

Trousseau’s

Chvosteks’s

54
Q

Hypocalcaemia Clinical Effects

Tetany, carpo-pedal spasm, generalized seizure, Laryngospasm, ______-reflexia, paraesthesiae _____tension, cataract, cardiac arrhythmias with prolonged _________ on ECG.

A

hyper; hypo

Q-T interval

55
Q

Hypocalcaemia Clinical Effects

Trousseau’s Sign:______ and _______ evoked by _______________ to 10-20mmHg above systolic blood pressure for _________

A

Carpopedal spasm and tetany

inflating a blood pressure cuff

3-5minutes.

56
Q

Hypocalcaemia Clinical Effects

Chvosteks’s sign can be elicited by tapping the ________ (anterior or o
posterior?) to the ear, when (ipsilateral or contralateral ?) facial muscle contraction may occur.

A

facial nerve

Anterior

ipsilateral

57
Q

Hypocalcaemia can be classified into:

  1. Hypocalcaemia with ________
  2. Hypocalcaemia with ___________
A

hypophosphataemia

hyperphosphataemia

58
Q

Hypocalcaemia with hypophosphataemia

Causes
In ______ hyperparathyroidism there is _____ and ________ deficiency causing hypocalcaemia
or _______ of calcium, vitamin D and

A

secondary

vitamin D and phosphate

inadequate intake

59
Q

Hypocalcaemia with hypophosphataemia

Other Causes include
Impaired __________ of _______ in ________

Impaired _______ of vitamin D 1,25(OH)2 D3 due to _____ disease.

Increased _______ of vitamin D due to ________ therapy.

In renal tubular disorders of _______ reabsorption.

A

absorption of vitamin D in steathorhoea

metabolism; renal

inactivation

phosphate

60
Q

Causes of Hypocalcaemia with Hyperphosphataemia

1)Renal dysfunction: ________ renal failure cause hyperphosphataemia because the __________ is affected and its synergestic effect on ____ is lost.

____________ develops within a few days of the onset of renal damage followed by _________.

.

A

acute and chronic

1-  - hydroxylation; PTH

Hypocalcaemia

hyperphosphataemia

61
Q

Causes of Hypocalcaemia with Hyperphosphataemia

_______ ______parathyroidism usually caused by _____ to the _______ during ___________.

A

Primary; hypo; surgical damage

parathyroids; partial thyroidectomy

62
Q

Causes of Hypocalcaemia with Hyperphosphataemia

Pseudohypoparathyroidism

This is a rare in born error of metabolism with an impaired response of ______________________ to ________

There is ________________ to circulating parathyroid hormone

The PTH concentration is _____ but with
hypocalcaemia and hyperphosphataemia

A

both kidney and bone to PTH

end organ resistance

raised

63
Q

Treatment of Hypocalcaemia

Mild hypocalcaemia - ________ and _______

A

oral calcium and vitamin D supplementation.

64
Q

Treatment of Hypocalcaemia

Hypocalcaemia with life threatening symptoms such as cardiac arrhythmias, seizure, severe tetany or laryngospasm -

Give _______ as 10mls of 10% _______ for over _______ then continue with ______________

A

IV calcium; calcium gluconate

5 minutes

oral supplementation.

65
Q

Phosphate Metabolism

Phosphate is a (mono or di?) valent (anion or cation?) .

80% is found in the _______
20% is distributed in __________________

A

Di; anion

bony skeleton.

soft tissues and muscle.

66
Q

Phosphate Metabolism

______% is found in the bony skeleton.

______ % is distributed in soft tissues and muscle.

Phosphate is the major _____cellular anion.

A

80

20

intra

67
Q

__________ is the major intracellular anion.

A

Phosphate

68
Q

Phosphate Metabolism

(Acidosis or Alkalosis ?) can result in the shift of phosphate out of the cell in to the plasma.

A

Acidosis

69
Q

Phosphate Metabolism

Protein rich foods, cereals and nuts are rich source of dietary phosphate.
Phosphate is ____% excreted via the renal route.

A

90

70
Q

Functions of phosphate

Intracellular ______

_______ buffers – buffering ______ ions in _______.

It has structural role as a component of _____,_________, and ________.

A

buffer

Urine; hydrogen; urine

phospholipids, nucleo-proteins and nucleic acids

71
Q

Functions of phosphate
Intracellular buffer

Plays a central role in cellular metabolic pathways, including ________ and ________

_________ regulates hemoglobin oxygen dissociation.

Component of nucleotides such as _______.

A

glycolysis and oxidative phosphoxylation.

2, 3 DPG

ATP

72
Q

Treatment of Hyperphosphataemia
1. Use of ______________ agents e.g. ______ or ________

  1. ____dialysis or ________ dialysis may be indicated
A

oral phosphate binding

magnesium hydroxide or calcium carbonate

Hemo; peritoneal

73
Q

Hypophosphataemia
Causes

Cellular redistribution

– Intravenous _______
– Alkalemia
–______ administration

A

glucose

Insulin

74
Q

Hypophosphataemia
Causes

Poor _______
_________ states
Chronic _____-
Renal tubular (acidosis or alkalosis?)
_______parathyroidisms

A

intake

Malabsorbtion

alcoholism; acidosis

Hyper

75
Q

Magnesium Metabolism

Predominantly an _____cellular ___valent ____ion.

It is an essential _______ to many enzymes as well as being important for _______ function.

A

intra; di; cation

co factor

Membrane

76
Q

Magnesium Metabolism

It can act as an antagonist to _______ in cellular responses.

Magnesium is largely absorbed in the _____________ and its absorption (is or is not ?) vitamin D dependent.

A

calcium

upper small intestine ; Is not

77
Q

Magnesium Metabolism

Cereals, nuts and vegetables are rich dietary sources of magnesium.

It is eliminated in _____ and via the ______ as well.

A

faeces; kidney

78
Q

Magnesium Metabolism

__________,______, and ________ are thought to be important in its homeostatic control.

A

PTH, insulin and calcitonin

79
Q

Hypermagnesaemia Causes

Increased _____

Impaired __________

__________ Causes

A

intake

renal excretion

Miscellaneous

80
Q

Hypermagnesaemia Causes

Increased intake
_______
_________
____________

Impaired renal excretion
_______ and ___________

Miscellaneous Causes
_________
__________

A

Antacids
Purgatives
Parenteral nutrition

Acute and chronic renal failure

Hypothyroidism
Adrenal insufficiency

81
Q

Clinical consequences of hypermagnesemia

Clinical consequences usually manifest at Mg. concentration >___ mmoles/L

Cardiac _______ ,Cardiac _____

Seizures, _____ reflexia

Paralytic ileus, Nausea

Respiratory _______

_____tension

A

2

arrhythmias; arrest

Hypo

depression

Hypo

82
Q

Management of severe Hypermagnesemia

10ml of 10% _________ giving slowly

_____/______ infusion

________, if above fail.

A

calcium gluconate

Insulin/glucose

Dialysis

83
Q

The symptoms of hypomagnesaemia are very different from those of hypocalcaemia.

T/F

A

F

similar

84
Q

Hypomagnesaemia

Hypomagnesaemia can result in cardiac ________ , _______ sensitivity, ________ discomfort, anorexia and neuromuscular sequelae such as ____,______,______,______ etc.

A

arrhythmias; digoxin

Abdominal

parasthesia, vertigo, tetany, seizures, irritability

85
Q

Hypomagnesaemia

Severe hypomagnesaemia can lead to ______calcaemia due to decreased _____ release and activity.

A

hypo

PTH

86
Q

Long term magnesium deficiency may be a risk factor for coronary artery disease.

T/F

A

T

87
Q

Some data suggest that reduced magnesium intake is associated with hypertension and insulin resistance.

T/F

A

T

House Clinical Pathology (45 decks)

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