Calcium and Phosphate Disorders

Question 1

what hormones are released in response to hyper/hypo calcemia?

Answer 1

• high blood Ca++: causes release of calcitonin
  
  • calcitnon promotes deposition of blood Ca++, thus lowering blood Ca++
• low blood Ca++: promotes release of PTH
  
  • ​PTH promotes:
    
    • Ca+ reabsorption at the distal tubule
    • Ca++ absorption from bone/gut
    • relase of calitriol, which:
      
      • increases synthesis of CPB
      • promotes Ca++ absorption from gut/bone

Question 2

what would increase Ca++ absorption from the gut?

Answer 2

• puberty
• pregnancy/lactation
• Vitamin D excess
• acromegaly

Question 3

what would decrease Ca++ absorption of gut?

Answer 3

High vegetable & high fat diet

Steroids

Senescence

Gastrectomy

Malabsorption

Diabetes

Renal Failure

Question 4

how does acidosis/alkalosis effect presence of calcium in the urine

Answer 4

• acidosis: hypercalciuria
• alkalosis: hypercalciuria

Question 5

which diruetic corresponds to which level urine Ca++ level

Answer 5

Loop - hypercalciuria

Mannitol – hypercalciuria

Thiazides – hypocalciuria

Amiloride - hypocalciuria

Question 6

false hypercalcemia vs true hypercalcemia

Answer 6

False Hypercalcemia: Increase total Ca++ resulting from increase total proteins

True Hypercalcemia: Increase in free plasma Ca++. This leads to clinically relevant hypercalcemia

• if free plasma Ca++ not known: obtain plasma albumin level to estimate total calcium

Question 7

what are the major causes of hypercalcemia?

Answer 7

“chimpanzees”

-Calcium supplementation

• Hyperparathyroidism
• Idiopathic
• Milk-alkali syndrome
• Paget’s disease
• Addison’s disease
• Neoplastic disease
• Zollinger-Ellison syndrome
• Excessive vitamin A
• Excessive vitamin D
• Sarcoidosis-think granulomatous disease

Question 8

what are major clinical manifestations of hypercalcemia?

Answer 8

• bones, stones, grones, psychiatric overtones
  
  • bones = abnormal bone remodeling/fracture risk
  • stones = increased risk for kidney stones
  • groans = abdominal cramping, nausea, ileus, coonstipation
  • psychiatric overtones

Question 9

treatments for hypercalcemia:

Answer 9

• Saline Infusion (0.9% NS)
• Loop Diuretics once rehydrated
• Dialysis
• Calcitonin (promotes calcium deposition) – short term effects
• for cancer:
  
  • Steroids – beneficial in cancer
  • IV Bisphosphonates – treatment of choice in cancer
    
    • Inhibit bone reabsorption, inhibits calcitriol synthesis (calcitriol synthesis is usually stimulated by PTH and increases plasma Ca++)

Question 10

major causes of hypocalcemia

Answer 10

Chronic and acute renal failure

Vitamin D deficiency-can lead to osteoporosis

Magnesium deficiency

Acute pancreatitis

Hypoparathyroidism and pseudohypoparathyroidism

Infusion of phosphate, citrate, or calcium-free albumin

Question 11

nueromuscular manifestations of hypocalcemia

Answer 11

• troesseu’s sign: pt is unable to control finger movements when a blood pressure cuff is placed on their arm
• Chostek’s sign: facial switch

Question 12

cardiovascular manifestations of hypocalcemia

Answer 12

• Hypotension
• Decreased Cardiac Output
• Ventricular ectopic activity
• QT interval prolongation - monitor this patient with an EKG closeley

Question 13

symptoms of hypocalcemia

Answer 13

Most patients will be asymptomatic or report symptoms of intermittent paresthesia (numbness and tingling) of the hands and feet or perioral numbness

Question 14

general treatment for hypocalcemia

Answer 14

• leafy greens
• calcium supplements (1-3 g/day)
• IV
  
  • only indicated in patients with symptomatic hypocalcemia OR ionized calcium levels below 0.65 mmol/L

Question 15

major causes of hyperphosphatemia:

Answer 15

• enhanced metabolism
  
  • hemolysis
  • rhabdomyolysos
  • malignant hyperthermia
• neoplastic disease
  
  • leukemia, lymphoma
• renal failure
• hypothyroidism, psuedohypothyroidism

Question 16

major clinical manifestations of hyperphosphatemia

Answer 16

• formation of insoluble calcium-phosphate complexes that deposit in:
  
  • soft tissues
  • joints (should in picture)
  • kidneys
• hyperphosphatemia can actually cause acute hypocalcemia, resulting in:
  
  • seizures
  • tetany

Question 17

treatment for hyperphosphatemia

Answer 17

• Oral phosphate binders
  
  • Aluminum Salts (up to 3gms/daily)
  • Calcium Salts (up to 8gms/daily) - dont give in someone with hypercalcemia
    
    • PhosLo
  • Non-Calcium Binders
    
    • Renagel of Fosrenal
  • Magnesium Salts (up to2-3gms/day) - dont give in someone with hypermagnesemia

Question 18

what is considered severe moderate/severe hypophosphatemia

Answer 18

• moderate: decrease of 2.5- 1 mg/dl
• severe: decrease of less than 1.0 mg/dl

Question 19

causes of hypophosphatemia

Answer 19

• low intake
  
  • this is rarely due to patients diet.
  • if patient does have hypophosphatemia due to low diet, is it likely indicative of a malabsorption issue
• increased excretion:
  
  • likely due to PTH
    
    • (in phys we learned that the combined effects of PTH leads ot no change in plasma phosphate, idk)

Question 20

clinical manifestations of hypophosphatemia

Answer 20

Metabolic Encephalopathy

2) RBC dysfunction – may cause hemolysis
3) Leukocyte dysfunction
4) Thrombocytopenia
5) Decreased muscle strength and myocardial contractility.

Question 21

treatment of hypophosphatemia

Answer 21

1) 2)

Oral phosphate salts Neutraphos

IV phosphorus

a) Severe (<1.0mg/dl) in critically ill – 0.08-0.16mmol/kg IV over 2-6 h
b) Moderate (1.0-2.5mg/dl) on ventilator – 0.08-0.16mmol/kg IV over 2-6 h
c) Moderate (1.0-2.5mg/dl) not on ventilator – oral treatment with 1,000 mg/day
d) Mild – treat with oral 1,000 mg/day

Question 22

major causes of hypermagnesemia

Answer 22

• renal insufficiency
• hemolysis
  
  • concentration in erythrocytes - 3x greater than the serum
  • will rise 0.1/ mEqL for every 250 mL of erythrocytes
  • expected only in massive hemolysis

Question 23

clinical manifestations of hypermagnesemia

Answer 23

• cardiac conduction delays
• depressed contractility
• vasodilation
• early symptoms include loss of deep tendon reflexes (hyporeflexia) and can progress to flacid paralysis

Question 24

treatment for hypomagnesimia

Answer 24

■ Hemodialysis - treatment of choice

■ IV calcium gluconate (1 g IV over 2 to 3 minutes)

■ Fluids + furosemide