1 / 20

MLAB 2401: Clinical Chemistry Keri Brophy -Martinez

MLAB 2401: Clinical Chemistry Keri Brophy -Martinez. Overview: Mineral and Bone Metabolism. Calcium Homeostasis . Organs involved Small intestine Skeleton Hydroxyapatite ( calcium+ phosphorus+ hydroxide) Kidneys Origin Diet Reservoir Bone. Forms of Calcium. Bound to albumin–45%

lewis
Download Presentation

MLAB 2401: Clinical Chemistry Keri Brophy -Martinez

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MLAB 2401: Clinical ChemistryKeri Brophy-Martinez Overview: Mineral and Bone Metabolism

  2. Calcium Homeostasis • Organs involved • Small intestine • Skeleton • Hydroxyapatite • ( calcium+ phosphorus+ hydroxide) • Kidneys • Origin • Diet • Reservoir • Bone

  3. Forms of Calcium • Bound to albumin–45% • Reversible process • Binding is pH dependent • Free “ionized”–50% • Complexes with anions -5%

  4. Ionized Calcium • Free calcium in blood • Tightly regulated • Biologically active form • Advantage • Not associated with proteins or anions

  5. Functions of Calcium • Nerve impulse transmission • Cofactor in certain enzymes • Coagulation of blood • Skeletal mineralization • Preservation of cell membrane integrity and permeability

  6. Regulation of Calcium Homeostasis • Parathyroid hormone- PTH • Vitamin D3 • Calcitonin

  7. Parathyroid Hormone- PTH • Originates from the parathyroid gland • Secretion based on levels of free calcium • Activities/Roles • Stimulation of osteoclastic bone reabsorption and release of calcium and phosphate from bone • Stimulation of calcium reabsorption and inhibition of phosphate reabsorption from the renal tubules • Stimulation of renal production of 1,25(OH)2 vitamin D3, which increase intestinal absorption of calcium and phosphate

  8. Regulation of Calcium Homeostasis

  9. Vitamin D3/ Cholecalciferol • Synthesis occurs in skin, liver, kidneys • Affects gut, bone, and parathyroid • Actions/ Roles • Increases plasma calcium and phosphate concentration by increasing the absorption of calcium and phosphate from the gastrointestinal tract • Increases bone resorption and enhances the effects of PTH in the nephron to promote renal tubular calcium reabsorption • Stimulates osteoclasts to metabolize bone calcium

  10. Vitamin D: Where Does it Come From? • Sources of: • Diet • Animal tissues and products ( liver) • Irradiated milk • Sunlight

  11. Calcitonin • Secreted by the thyroid gland • Secreted when blood calcium rises • Inhibits PTH and Vitamin D • Inhibits bone resorption, promotes bone formation

  12. Phosphorous • Origin • Diet • Bone • Phosphate ion is distributed equally. • Intracellular • Component of macromolecules • Extracellular • Inverse relationship with Calcium

  13. Functions of Phosphorous • Component of bones & teeth • Essential part of cell membranes • Contributes to enzyme function • Storage and transfer of energy • Component of many compounds

  14. Phosphorous Regulation • Kidneys • Excrete or reabsorb • Other factors • PTH • Increases renal excretion • Vitamin D increases levels • Phosphate absorption in intestine • Phosphate reabsorption in kidneys • Growth Hormone, calcitonin, acid-base status

  15. Magnesium • 2nd most abundant intracellular cation • Location • 50-60% found in bone • 40-50% muscle & soft tissue • 1% in the RBC • Origin • Diet • Nuts, hard water, meat, green vegetables, fish, dry cereal

  16. Forms of Magnesium • Free or ionized (~55%) • Bound to proteins (~30%) • Complexed with phosphate, citrate and other ions (~15%)

  17. Functions of Magnesium • Important co-factor in reactions using ATP • Carbohydrate metabolism • Muscle contraction • Blood coagulation • Membrane stabilization • Nerve conduction • Maintenance of potassium

  18. Magnesium Regulation • Primary regulatory factor • Amount of magnesium in the plasma • Regulatory control • Kidney • Excrete or reabsorb magnesium depending on condition • Parathyroid hormone • Increases renal reabsorption • Enhances absorption in intestines

  19. References • Bishop, M., Fody, E., & Schoeff, l. (2010). Clinical Chemistry: Techniques, principles, Correlations. Baltimore: Wolters Kluwer Lippincott Williams & Wilkins. • http://rickets.stanford.edu/ • http://scrink.com/blog/wellness/2009/02/vitamin-d-cold-flu-correlation.html • Sunheimer, R., & Graves, L. (2010). Clinical Laboratory Chemistry. Upper Saddle River: Pearson .

More Related