Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Clinical Pathology > Disorders of calcium, phosphate & magnesium > Flashcards

Disorders of calcium, phosphate & magnesium Flashcards

1
Q

What is the physiological importance of calcium?

A
  • Muscle contraction
  • Neuronal excitation
  • Blood clotting
  • Enzyme activity (Na/K ATPase)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the physiological importance of phosphates?

A
  • Intracellular signalling
  • ATP
  • Cellular metabolic processes (glycolysis)
  • Predominantly intracellular
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the physiological importance of magnesium?

A
  • Enzymatic function
  • Regulates ion channels
  • Cofactor for ATP
  • Neuromuscular excitability
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What 2 factors control calcium?

A
  • PTH

- Vit D & metabolites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the normal range of calcium?

A

2.20-2.60

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is total calcium made up of? Describe each component

A 
Total= Ionised + bound + complexed
I= active, Ca sensing receptor, cellular effects, regulation of PTH
B= inactive, albumin main binding protein
C= salts- Ca phosphate & Ca citrate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is adjusted calcium?

A

Calcium values corrected for changes in albumin (range stays the same)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are problems with lab measurements for calcium?

A
  • Doesn’t reflect ionised Ca
  • pH influences ionised Ca
  • Total Ca affected by albumin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What clinical conditions can cause altered binding of Ca to albumin?

A

-Acidosis= reduces Ca-albumin
-Alkalosis= increases Ca-albumin
Ca & H+ ions compete for albumin binding sites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the effects of pH change/acidosis on Ca levels?

A
  • Inc ionised Ca

- Dec bound Ca

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the effects of pH change/alkalosis on Ca levels?

A
  • Dec ionised Ca

- Inc bound Ca

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the clinical implications of pH change on Ca?

A
  • Alkalosis, hyperventilation can precipitate tetany

- Hypocalcaemic patients with acidosis- asymptomatic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are effects of changes in binding proteins on Ca?

A
  • Total Ca reduced

- reduced bound calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the pathophysiology of calcium

A
  • Disorders of homeostatic regulators (PTH, Vit D)
  • Disorders of skeleton (bone mets)
  • Disorders of effector organ (GI-malabsorption)
  • Diet
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the endogenous & exogenous factors affecting vitamin D?

A
  • Endo= aging, skin colour

- Exo= ozone, sunscreen & clothing, time of day, diet & supplements, latitude & season

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What factors cause vitamin D levels to fall?

A
  • Age
  • BMI
  • Body fat
17
Q

Describe the mechanism of the parathyroid hormone loop

A
  • Parathyroid hormone produce PTH
  • Acts on bones, kidneys, GI
  • Positive feedback
  • Calcium produced
  • As plasma levels inc acts as negative feedback on parathyroid glands
18
Q

How does PTH act on bones, GI and kidneys?

A
  • Bones= Inc Ca turnover with net resorption
  • GI= Vit D inc, Ca absorption
  • Kidneys= Dec Ca clearance & inc phosphate excretion
19
Q

What are causes of hypocalcaemia?

A
  • Hypoproteinaemia
  • Inadequate intake of Ca
  • Vit D deficiency (renal/hepatic disease, dietary, end organ it D resistance)
  • Hypoparathyroidism (1° or 2° to Mg depletion)
  • Pseudohypoparathyroidism (end organ PTH resistance)
20
Q

What are causes of hypercalcaemia?

A
  • Hyperparathyroidism
  • Malignancy (lytic lesions)
  • Drugs
  • Vit D excess (sarcoidosis, cholecalciferol)
  • Bone disease & immobilisation
21
Q

What are causes of phosphate deficiency?

A
  • Hyperparathyroidism
  • Excess losses (GI, diabetes, renal tubular damages)
  • Poor intake (malnutrition)
  • ECF/ICF redistribution
22
Q

What are symptoms of phosphate deficiency?

A
  • Haemolysis
  • Thrombocytopenia
  • Poor granulation function
  • Severe muscle weakness
  • Respiratory muscle failure
  • Rhabdomyolysis
  • Renal dysfunction
  • Confusion
  • Irritability
  • Coma= metabolic encephalopathy
23
Q

What are 40% of hypomagnesaemia cases associated with?

A

Hypokalaemia

24
Q

What are causes of magnesium depletion?

A
  • Renal: Drugs (antibiotics, chemo, diuretics), hypercalcaemic states, diuretic phase of acute tubular necrosis
  • GI: malnutrition, diarrhoea, malabsorption, IV nutrition
25
Q

What are the effects of magnesium depletion? (Cells, bio and endocrine)

A
  • Cellular: reduced mitochondrial respiration, imparied phosphorylation, defective Na/K ATPase activity, impaired DNA synthesis
  • Bio: hypokalaemia/calcaemia/phosphataemia
  • Endocrine: impaired PTH release, PTH resistance in bone
26
Q

What are the clinical features of magnesium depletion?

A
  • Cardiac irritability
  • Reduced contractility
  • Tetany
  • Hyper-reflexia
  • Ataxia/vertigo
  • Psychosis/depression
  • Muscle weakness/fibrillation
  • Myopathic EMG

Clinical Pathology (56 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions