1. Chapter 14 Calcium, Magnesium, and Phosphate ，
Pan Baishen

2. Content CALCIUM Hypoparathyroidism Renal Diseases Neonatal Monitoring
Monitoring in Surgery and Acute Care
Critically Ill Patients
Hypomagnesemia

3. Content MAGNESIUM Critical Care Cardiac Disorders
Drug Effects on Magnesium Concentration
Diabetes Mellitus
Alcoholism
Other Diseases

4. Content
PHOSPHATE
Hypophosphatemia
Hyperphosphatemia

5. The electrolytes calcium, magnesium, and phosphate are the principal inorganic constituents of bone and are vital in the function of membranes, hundreds of enzymes, genetic regulation, muscle contraction, and energy utilization.

6. CALCIUM-1
Of all the calcium in the body, 99% is in the bone. The remaining 1% is mostly in the blood and other extracellular fluids.
Calcium circulates in the blood is several forms:
45% to 50% free ionized
40% to 45% bound to protein
10% to 15% bound to anions

7. CALCIUM-2
Three hormones are known to participate in serum calcium regulation, and have rates of secretion that depend on ionized calcium concentration.
parathyroid hormone (PTH)
1,25 dihydroxyvitamin D
calcitonin

8. CALCIUM -3

9. CALCIUM-4 Calcium in blood is distributed among several forms ：
About 45% circulates as ionized calcium
40% is bound to anionic sites on protein
15% is bound to anions

10. HYPOCALCAEMIC DISORDERS

12. HYPOCALCAEMIC DISORDERS-1
Hypoparathyroidism
Most cases of hypocalcemia from hypoparathyroidism result from surgical removal of tissue during parathyroid or thyroid surgery
Pseudohypoparathyroidism is a condition in which renal cells do not respond to PTH

13. HYPOCALCAEMIC DISORDERS-2
Renal Disease
In renal glomerular disease，ionized calcium is changed independently of total calcium
In chronic renal disease, a marked increase in serum PTH levels ,in which phosphate binds calcium, or by altered vitamin D metabolism

14. HYPOCALCAEMIC DISORDERS-3
Neonatal Monitoring
The first type of neonatal hypocalcemia is associated with parathyroid immaturity and usually resolves by the first week of life
The second type of neonatal hypocalcemia is associated with both hyperphosphatemia and hypomagnesemia

15. HYPOCALCAEMIC DISORDERS-4
Monitoring In Surgery and Acute Care
In open-heart surgery when the heart is restarted
Administering calcium as a cardiotropic agent before giving drugs
During liver transplantation

16. HYPOCALCAEMIC DISORDERS-5
Critically Ill Patients
Sepsis
Thermal burns
Renal failure
Cardiopulmonary insufficiency

17. HYPOCALCAEMIC DISORDERS-6
Hypomagnesaemia
Inhibition of transport of PTH across the parathyroid gland membrane
Impairment of PTH action at its receptor site on bone
Interference with the action of vitamin D

18. HYPERCALCEMIC DISORDERS

20. HYPERCALCEMIC DISORDERS-1
Primary hyperparathyroidism
Ionized calcium is elevated more frequently than total calcium in subtle or asymptomatic hyperparathyroidism
Measuring PTH during operations on the parathyroid glands can determine if sufficient parathyroid tissue has been removed

21. HYPERCALCEMIC DISORDERS-2
Malignancy
PTHRP appears to be expressed in tumors, measurements of which ultimately may have clinical diagnostic value
Ionized and total calcium measurements have about equal utility in the detection of occult malignancy

22. CALCIUM-1
Total calcium determinations may be performed on either serum or heparinized plasma
In routine testing of serum, many automated analyzers give results that are comparable to atomic absorption. In urine and other fluids, atomic absorption still is preferred.

23. CALCIUM-2 REFERENCE RANGES FOR CALCIUM
mmol/liter
mg/dl
Total calcium
Child
Adult
Ionized calcium
At birth
Neonate

24. MAGNESIUM -1 effect on myocardial function and blood pressure
an essential activator of over 300 enzymes
complex of ATP is the substrate in energy production

25. MAGNESIUM -2
The average dietary intake of magnesium is 10 to 15 mmol/day
20% to 63% of the dietary magnesium can be absorbed in the small intestine
The overall regulation of body magnesium is controlled largely by the kidney

26. MAGNESIUM-3 The human body contains about 1 mol (24 g) of magnesium
about 50% in the skeleton
relatively high concentrations in skeletal muscle, liver, and myocardium

27. HYPOMAGNESEMIA-1 Critical Care
Among chronic diseases, alcoholism, liver disease, and carcinoma were commonly associated with hypomagnesemia
Magnesium was the most common electrolyte abnormality found among pediatric intensive-care unit patients

28. HYPOMAGNESEMIA-2 Cardiac Disorders
Magnesium deficiency has been associated with coronary vasospasm, arrhythmias, acute infarction, and sudden death
In patients undergoing surgery with cardiopulmonary bypass, plasma ionized magnesium was decreased by 24 hours after bypass

29. HYPOMAGNESEMIA-3 Drug Effects on Magnesium Concentration
Several drugs, including diuretics, gentamicin and other aminoglycoside antibiotics, cisplatin, and cyclosporine result in hypomagnesemia

30. HYPOMAGNESEMIA -4 Diabetes Mellitus
Magnesium loss secondary to ketoacidosis and glycosuria
abnormal intracellular­extracellular distributions of magnesium caused by hormonal imbalances

31. HYPOMAGNESEMIA -5 Alcoholism
Renal magnesium losses and decreased muscle magnesium content
dietary deficiency, ketosis, vomiting, diarrhea, and hyperaldosteronism

32. HYPOMAGNESEMIA-6 Other Diseases Pregnancy
Premature labor and preeclampsia or eclampsia
Neonatal seizures
Renal stone formation and other renal calcification
Paget's disease

33. MAGNESIUM -1 The patient should fast before collection of blood
Hemolyzed samples are not acceptable
The anticoagulants must not be used

34. MAGNESIUM -2
About 30% of magnesium is protein bound, total magnesium may not reflect the physiologically active magnesium
serum concentration will not necessarily reflect the status intracellular magnesium

35. MAGNESIUM-3 Methods: atomic absorption spectroscopy
colorimetric methods using either calmagite or methylthymol blue
a dry-slide colorimetric method using a formazan dye and a calcium chelator
A magnesium load test

36. MAGNESIUM -4 REFERENCE RANGES FOR MAGNESIUM
mmol/liter
Total magnesium
　Serum (newborns)
　Serum (adults)
　Erythrocytes
　CSF
　Urine
1-5 mmol/day
Ionized magnesium
　Blood
(AVI. analyzer)
(Nova analyzer)

37. PHOSPHATE-1
The genetic materials DNA and RNA are complex phosphodiesterases
The most important reservoirs of biochemical energy are ATP, creatine phosphate, and phosphoenol pyruvate

38. PHOSPHATE -2
About 80% of the 700 to 800 grams of phosphate in the body are contained in bone, mostly in the form of hydroxyapatite [Ca10(PO4)6(OH)2]
The kidney plays an important role in the regulation of serum phosphate concentration

39. HYPOPHOSPHATEMIA-1 Transcellular Shift
the movement of glucose into cells is accompanied by phosphate
GI losses
diarrhea and vomiting
Renal losses
primary hyperparathyroidism, diuretics, hypomagnesemia, or defects in renal tubular absorption of phosphate

40. HYPOPHOSPHATEMIA-2 Mixed causes Diabetic ketoacidosis Acidosis
Alcoholism

41. HYPERPHOSPHATEMIA-3 Renal failure Severe infections Intensive exercise
Neoplastic diseases

42. PHOSPHATE -1 The patient should fast before collection of blood
Hemolyzed samples are not acceptable
Intravenous administration of glucose or fructose lowers serum phosphate

43. ANS, stannous chloride, ferrous ammonium sulfate
PHOSPHATE-2
Methods:
Reducing Reagent
Absorption Peak
ANS, stannous chloride, ferrous ammonium sulfate
660nm
Semidine HCl
680nm

44. PHOSPHATE-3 REFERENCE RANGES FOR PHOSPHATE
Serum Phosphate
mg/dL
mmol/L
Newborn (1-2 days)
Infant
Child
Adult male
Adult female

45. Thanks!