Hyperphosphatemia/Hypophosphatemia Flashcards Preview

Endocrine system > Hyperphosphatemia/Hypophosphatemia > Flashcards

Flashcards in Hyperphosphatemia/Hypophosphatemia Deck (16):
1

Hyperphosthatemia

high phosphate levels in the blood

2

Function

1. 85% in bones
- combines with calcium to form hydroxyapatite - makes bones hard
2. 1% EXTRACELLULAR
3. 14% INTRACELLULAR
• phosphorylation
• ATP
• Part of DNA/RNA

3

Phosphate and calcium

Calcium and phosphate in the blood are bound togather
1. If Calcium levels fall
2. Parathyroid hormone is released
3. This hormone frees up both Calcium and phosphate from the bones

4

Causes of hyperphosphatemia
( ASSOC W PARATHYROID/CALCIUM(

1. Acute/chronic kidney disease - gfr falls thus less excretion means more phosphate build up

2. Kidneys unable to reabsorb calcium so more gets excreted
-> parathyroid hormone is released by gland
-> Secondary parathyroidism
-> Increased release of phosphate and calcium ions
-> Renal osteodystrophy - bones become weak and thin in people with chronic kidney disease
3. Pseudohypoparathyroidism - receptors do not respond to parathyroid hormone due to genetic defect
-> Calcium gets lost and phosphate build up instead
-> Same pattern as in kidney disease
4. Hypoparathyroidism

5

Causes of Hyperphosphatemia
( Excess build up in blood)

5. Excessive intake and absorbtion in GI tract

6. Mass cell apoptosis
-> causes release of intracelllular phosophate

7. Respiratory acidosis
• co2 levels rise as a result of drop in ventilation
• CO2 diffuses into cell to react and form carbonic acid
• Lowers cellular Ph as it gets more acidic
• Lower pH inhibits glycolysis
• Less phosphate pulled out of the blood
• Phosphate levels in the blood rise

8. Diabetic ketacidosis
• Low insulin in blood
• Cells extract less phosphate from the blood ( mech unclear)
• Phosphate builds up

6

Symptoms

Mild cases -> no symptoms
Severe cases
1. Neurons become more excitable
• Spontaneous firing -> Tetany (involuntary muscle contraction)
• Causes Chvostek's sign / Trousseau's sign
2. Tingling around the mouth
3. Seizures

4. Bone pain
5. Bone like crystals/under skin/blood vessel walls/joints/ - excess phosphate finds and binds to calcium
• Nephrocalcinosis - long term calcification of kidney

7

Diagnosis

Phosphate levels above 4.5 mg/dl

8

Treatment

• Decreased intake - avoid food with a lot of phosphate
• Medication - phosphate binders
- Increase excretion of phosphate - intravenous fluids/ loop diuretics

9

Hypophosphataemia

low phosphate levels in the blood

10

Hypophosphataemia causes
( EXCESS PO4- lost)


• Primary hyperparathyroidism - too much parathyroid hormone release
- Excess phosphate is lost in the urine as it inhibits PO4 uptake
• Fanconi Syndrome
- Proximal convulated tubule lose capacity to reabsorb variety of solutes including phosphate
- excess secreted in urine

11

Hypophosphataemia causes
( not enough absorbed in the GI tract)

1. Alcohol - impairs absorbtion
2. Medication - antacids contain AL, Ca, Mg bind to negative Phosphate ion and block absorbtion

12

Hypophosphataemia
( not enough in the diet/Excess extraction from blood)

• Malnourishment /Anorexia nervosa
- blood glucose is low and cellular metabolism slows down considerably
- Refeeding syndrome - when nourishment is recieved, phosphate ions are rapidly taken up for ATP production leaving v little in blood
- Risk of arrythmias and neurological problems

• Diabetes - not enough insulin in produced
- diabetic ketoacidosis developed
- insulin causes extraction of phosphate from blood
- phosphate levels fall

• Respiratory Alkalosis
- increased PH inside cell
- Glycolysis stimulated - this process requires alot of phosphate
- Pull excess phosphate out of blood
- Hypophosphataemia

13

Symptoms of hypophosphataemia

Severe
• Muscle weakness
• Osteomalacia - weak bones
• Rhabdomylosis - kidney damage due to muscle breakdown
• Altered mental status
• Hyper calcaemia symptoms

14

Symptoms of hypercalcaemia

1. Stones - kidney stones
2. Bones - pain pain from chronic demineralisation
3. Thrones - polyuria
4. Groans - constipation and muscle weakness
6. Psychiatric overtones - depressed

15

Diagnosis of phosphate

• Blood levels below 2.5 mg/dl

16

Treatment

• Intravenous/Oral PO4
• Malnutrition - gradual increase of caloric intake to avoid refeeding syndrome