Calcium, Phosphate , Magnesium Flashcards by Iseoluwa Ojo

Disorders of calcium metabolism are (common or rare?) in clinical practice and they are closely associated with disorders of _______ and ______ metabolism

Common

phosphate and magnesium

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Distribution of Body Calcium

The total body calcium depend on the amount _________ and the amount _________

absorbed from the diet

lost from the body

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Distribution of Body Calcium

About ______% of Calcium in the body is part of bone.

The remaining __% is mostly in the _______ and ______

1; blood and ECF

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Distribution of Body Calcium

The extra-osseous fraction is very important because of its effect in ____________ and ___________

neuromuscular excitability and cardiac muscle contraction.

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Distribution of Body Calcium

The reference interval for plasma total calcium concentration is _______-_______ mmol/L

2.15-2.55

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Calcium in blood is distributed among several forms.

T/F

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Distribution of Body Calcium

About 45% circulates as _________

40% is ________________, mostly ______

15% is ______________ such as _________

free Calcium ions

bound to protein, mostly albumin

bound to anions, such as HCO3 , citrate, PO4 , and lactate.

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Distribution of Body Calcium

About ____% circulates as free Calcium ions

_____% is bound to protein, mostly albumin

____% is bound to anions, such as HCO3 , citrate, PO4 , and lactate.

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free Calcium ions

referred to as ______ Ca2

ionized

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Distribution of Body Calcium

The free ionized calcium is the physiologically (active or inactive?) fraction.

Active

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Distribution of Body Calcium

The albumin bound fraction is known as the physiologically (active or inactive?) fraction.

Inactive

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Distribution of Body Calcium

The ____________ calcium functions in neuromuscular excitability and cardiac muscle contraction
M

free ionized

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Distribution of Body Calcium

The reference interval for plasma free ionised calcium concentration is ______-____ mmol/L

1.1-1.4

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Control of Plasma Calcium
Factors involved in the control of calcium include:

_______ supply of calcium
________
Normal functioning _______
________ glands
Normal functioning ________.

Dietary

Vitamin D.

intestines

Parathyroid

kidneys

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Control of Plasma Calcium
Parathyroid Hormone

Secreted from the ________ gland

PTH is a _____ chain polypeptide containing _____ residues, the ____ N terminal amino acid largely determines its biological activity.

parathyroid

single; 84; 34

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Control of Plasma Calcium

Actions of PTH
1. It increases the plasma concentration of ____________ by stimulating _______ bone __________

On the kidneys, it causes decreased tubular re- absorption of ______ causing ____ and decreased ______ levels while it increases plasma ______ by increasing tubular reabsorption of ________.

calcium and phosphate; osteoclastic; resorption

phosphate; phosphaturia; phosphate

calcium; calcium

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Control of Plasma Calcium
The control of PTH depends on:

Plasma _________ concentration
_____cellular ______ concentration

free ionized calcium

Extra; magnesium

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plasma PTH conc. is _____eased by severe chronic hypomagnesaemia

decr

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Control of Plasma Calcium

•Parathyroid Hormone Related Protein

This is a peptide hormone that has a similar ________ with PTH at the biologically ________

It is actively increased in certain ______ causing humoral __________ of malignancy

amino acid sequence

active end.

tumours

hypercalcaemia

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Control of Plasma Calcium

Calcitonin

Calcitonin, which originates in the ______ cells of the ______ gland, is secreted when the concentration of Calcium in blood ____eases.

medullary; thyroid; incr

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Control of Plasma Calcium

Calcitonin exerts its calcium lowering effect by _________________________

inhibiting the actions of both PTH and vitamin D.

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Calcitonin is however secreted during normal regulation of the ionized Ca2 concentration in blood

T/F

not

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Calcitonin is secreted in response to a _____calcemic stimulus

hyper

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Control of Plasma Calcium

vitamin D –

Sources of vitamin D

Vitamin D3, aka ________, is obtained from the _________ or _______

cholecalciferol

diet or exposure of skin to sunlight

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Control of Plasma Calcium Vitamin D ____calciferol (vitamin D2) obtained from _____ in the _____ _____calciferol (vitamin D3) formed in the _____ by the action of ___________ on _____________

Ergo; plants; diet Chole; skin ultra violet light on 7 dehydrocholesterol

Control of Plasma Calcium Metabolism of Vitamin D Vitamin D is transported in blood bound to specific carrier protein – __________________ In the ____, cholecalciferol is hydroxylated to ——————————- by the enzyme __________.

the vitamin D binding protein. liver 25 hydroxycholecalciferol (25OHD3) 25- hydroxylase

Control of Plasma Calcium _______________ is the main circulatory form and store of the vitamin.

25 hydroxycholecalciferol (25OHD3)

Control of Plasma Calcium Vitamin D metabolism In the _____ renal tubular cells of the kidney, _______ undergoes a second hydroxylation to form the active metabolite - __________________

proximal 25OHD3 1,25 dihydroxycholecalciferol

Control of Plasma Calcium Vitamin D metabolism The production of 1,25(OH)2D3 by ________________ may be stimulated by (low or high?) plasma phosphate concentration and ____eased PTH concentration

1-alpha - hydroxylase Low incr

Control of Plasma Calcium Vitamin D metabolism The 1-alpha -hydroxylase activity is inhibited by ____phosphataemia and (low or high?) levels of free ionized calcium

hyper High

Control of Plasma Calcium Vitamin D metabolism The synthesis of the hormone 1,25 (OH)2 Vit D3 decreases in ____ disease and can lead to ____calcaemia.

renal hypo

Control of Plasma Calcium Actions of 1,25(OH)2 Vitamin D3 It Increases ____________ absorption by ___________ cells

calcium and phosphate intestinal mucosal

Control of Plasma Calcium Actions of 1,25(OH)2 Vitamin D3 It acts synergistically with _____ to stimulate ________ activity and release ______ from _____

PTH; osteoclastic calcium from bone.

The action of PTH on bone is impaired in the absence of 1,25(OH)2 Vitamin D3. T/F

PTH enhances _________ activity and therefore stimulation 1,25- (OH)2 Vit. D3 synthesis.

1- hydroxylase

Disorders of Calcium Metabolism: Hypercalcaemia Hypercalcaemia has clinical consequences Renal effects – renal damage, _____uria, renal calculi due to precipitation of ________ ______kalemia Neuromuscular effects – it (depresses or enhances?) neuromuscular excitability leading to ____tonia.

poly; calcium phosphate stones. Hypo; depresses hypo

calcium directly inhibits potassium reabsorption from the tubular lumen. T/F

Disorders of Calcium Metabolism Hypercalcemia CNS effects –______, anorexia, nausea and vomiting. GIT effect – _________, constipation and abdominal pain.

depression peptic ulceration

Disorders of Calcium Metabolism Hypercalcemia Cardiac effect – ECG changes with _________ of the Q-T interval and ________ of the T waves. At Ca >3.5mmoles/L, there is increased risk of sudden ________ or _________

shortening broadening cardiac arrest or ventricular arrhythmias.

Severe hypercalamia should be treated as a medical emergency. T/F

Causes of Hypercalcaemia _______ diuretics ____ metastasis ___________ abnormalities (Low or High?) bone turnover (Low or High?) levels of vitamin D

Thiazide Bony Parathyroid hormone High High

Causes of Hypercalcaemia Thiazide diuretics (________________) Bony metastasis- from breast, lung, prostate, kidney and thyroid carcinomas. Parathyroid hormone abnormalities- ————- and ______ High bone turnover-__________, prolonged _________

reduced calcium excretion primary and tertiary hyperparathyroidism thyrotoxicosis; immobilization

Causes of Hypercalcaemia Primary Hyperparathyroidism This is caused by ________________________ causing hypercalcaemia.

inappropriate secretion of PTH by the PTH glands

Causes of Hypercalcaemia It may be due to an ________, ________ or __________ of the parathyroid glands.

adenoma hyperplasia or carcinoma

Causes of Hypercalcaemia Tertiary Hyperparathyroidism This may occur if the parathyroid glands have been subjected to ________________ by ______________ which has been subsequently corrected.

long standing and sustained positive feedback hypocalcaemia of secondary hyperparathyroidism

Causes of Hypercalcaemia Tertiary Hyperparathyroidism The parathyroid glands ________, PTH secretion becomes _________ and not suppressed by ________ of ________

hypertrophy partly autonomous negative feedback of hypercalcaemia.

Causes of Hypercalcaemia Hypercalcaemia of Malignancy a)_________ of the _________ b)________________ of Malignancy

Malignant Disease of the Bone Humoral Hypercalcaemia

Causes of Hypercalcaemia Hypercalcaemia of Malignancy a)Malignant Disease of the Bone ———- from tumours of the breast, lungs, prostate, kidney and thyroid cause hypercalcaemia. Plasma ______ is also high from bone break down due to local action of malignant deposits The malignant deposits stimulate a local _______ reaction and hence plasma _________ activity is raised.

Bony metastasis phosphate osteoblastic alkaline phosphatase

Causes of Hypercalcaemia Hypercalcaemia of Malignancy B) Humoral Hypercalcaemia of Malignancy Some malignant tumors secret ________. This secretion is not subject to _________ by high plasma free ionized calcium concentration.

PTHRP normal feedback control

Drugs/Medication Various medication can cause hypercalcaemia such as _______ which decreases renal calcium excretion. Others include _______ and ________ Vitamin ___ Excess ___________ treatment of hypocalcaemia.

thiazides Lithium and Vitamin A. D Over enthusiastic

Causes of Hypercalcaemia Sarcoidosis The granulomatous tissue in sarcoidosis may _________________ , causing increased calcium absorption from the GIT. _____________ and _________ may also produce the same effect.

synthesize 1,25(OH)2 cholecalciferol Histoplasmosis and leprosy

Treatment of Severe Hypercalcaemia Re-________ Bisphosphonates e.g. ________ (Ca binders) ________ especially in Vit. D intoxication and sarcoidosis Calcitonin

hydration pamidronate Steroids

Hypocalcaemia Clinical Effects _______,_______ spasm, generalized ________ __________ Sign __________ sign

Tetany, carpo-pedal seizure Trousseau’s Chvosteks’s

Hypocalcaemia Clinical Effects Tetany, carpo-pedal spasm, generalized seizure, Laryngospasm, ______-reflexia, paraesthesiae _____tension, cataract, cardiac arrhythmias with prolonged _________ on ECG.

hyper; hypo Q-T interval

Hypocalcaemia Clinical Effects Trousseau’s Sign:______ and _______ evoked by _______________ to 10-20mmHg above systolic blood pressure for _________

Carpopedal spasm and tetany inflating a blood pressure cuff 3-5minutes.

Hypocalcaemia Clinical Effects Chvosteks’s sign can be elicited by tapping the ________ (anterior or o posterior?) to the ear, when (ipsilateral or contralateral ?) facial muscle contraction may occur.

facial nerve Anterior ipsilateral

Hypocalcaemia can be classified into: 1. Hypocalcaemia with ________ 2. Hypocalcaemia with ___________

hypophosphataemia hyperphosphataemia

Hypocalcaemia with hypophosphataemia Causes In ______ hyperparathyroidism there is _____ and ________ deficiency causing hypocalcaemia or _______ of calcium, vitamin D and

secondary vitamin D and phosphate inadequate intake

Hypocalcaemia with hypophosphataemia Other Causes include Impaired __________ of _______ in ________ Impaired _______ of vitamin D 1,25(OH)2 D3 due to _____ disease. Increased _______ of vitamin D due to ________ therapy. In renal tubular disorders of _______ reabsorption.

absorption of vitamin D in steathorhoea metabolism; renal inactivation phosphate

Causes of Hypocalcaemia with Hyperphosphataemia 1)Renal dysfunction: ________ renal failure cause hyperphosphataemia because the __________ is affected and its synergestic effect on ____ is lost. ____________ develops within a few days of the onset of renal damage followed by _________. .

acute and chronic 1-  - hydroxylation; PTH Hypocalcaemia hyperphosphataemia

Causes of Hypocalcaemia with Hyperphosphataemia _______ ______parathyroidism usually caused by _____ to the _______ during ___________.

Primary; hypo; surgical damage parathyroids; partial thyroidectomy

Causes of Hypocalcaemia with Hyperphosphataemia Pseudohypoparathyroidism This is a rare in born error of metabolism with an impaired response of ______________________ to ________ There is ________________ to circulating parathyroid hormone The PTH concentration is _____ but with hypocalcaemia and hyperphosphataemia

both kidney and bone to PTH end organ resistance raised

Treatment of Hypocalcaemia Mild hypocalcaemia - ________ and _______

oral calcium and vitamin D supplementation.

Treatment of Hypocalcaemia Hypocalcaemia with life threatening symptoms such as cardiac arrhythmias, seizure, severe tetany or laryngospasm - Give _______ as 10mls of 10% _______ for over _______ then continue with ______________

IV calcium; calcium gluconate 5 minutes oral supplementation.

Phosphate Metabolism Phosphate is a (mono or di?) valent (anion or cation?) . 80% is found in the _______ 20% is distributed in __________________

Di; anion bony skeleton. soft tissues and muscle.

Phosphate Metabolism ______% is found in the bony skeleton. ______ % is distributed in soft tissues and muscle. Phosphate is the major _____cellular anion.

80 20 intra

__________ is the major intracellular anion.

Phosphate

Phosphate Metabolism (Acidosis or Alkalosis ?) can result in the shift of phosphate out of the cell in to the plasma.

Acidosis

Phosphate Metabolism Protein rich foods, cereals and nuts are rich source of dietary phosphate. Phosphate is ____% excreted via the renal route.

Functions of phosphate Intracellular ______ _______ buffers – buffering ______ ions in _______. It has structural role as a component of _____,_________, and ________.

buffer Urine; hydrogen; urine phospholipids, nucleo-proteins and nucleic acids

Functions of phosphate Intracellular buffer Plays a central role in cellular metabolic pathways, including ________ and ________ _________ regulates hemoglobin oxygen dissociation. Component of nucleotides such as _______.

glycolysis and oxidative phosphoxylation. 2, 3 DPG ATP

Treatment of Hyperphosphataemia 1. Use of ______________ agents e.g. ______ or ________ 2. ____dialysis or ________ dialysis may be indicated

oral phosphate binding magnesium hydroxide or calcium carbonate Hemo; peritoneal

Hypophosphataemia Causes Cellular redistribution – Intravenous _______ – Alkalemia –______ administration

glucose Insulin

Hypophosphataemia Causes Poor _______ _________ states Chronic _____- Renal tubular (acidosis or alkalosis?) _______parathyroidisms

intake Malabsorbtion alcoholism; acidosis Hyper

Magnesium Metabolism Predominantly an _____cellular ___valent ____ion. It is an essential _______ to many enzymes as well as being important for _______ function.

intra; di; cation co factor Membrane

Magnesium Metabolism It can act as an antagonist to _______ in cellular responses. Magnesium is largely absorbed in the _____________ and its absorption (is or is not ?) vitamin D dependent.

calcium upper small intestine ; Is not

Magnesium Metabolism Cereals, nuts and vegetables are rich dietary sources of magnesium. It is eliminated in _____ and via the ______ as well.

faeces; kidney

Magnesium Metabolism __________,______, and ________ are thought to be important in its homeostatic control.

PTH, insulin and calcitonin

Hypermagnesaemia Causes Increased _____ Impaired __________ __________ Causes

intake renal excretion Miscellaneous

Hypermagnesaemia Causes Increased intake _______ _________ ____________ Impaired renal excretion _______ and ___________ Miscellaneous Causes _________ __________

Antacids Purgatives Parenteral nutrition Acute and chronic renal failure Hypothyroidism Adrenal insufficiency

Clinical consequences of hypermagnesemia Clinical consequences usually manifest at Mg. concentration >___ mmoles/L Cardiac _______ ,Cardiac _____ Seizures, _____ reflexia Paralytic ileus, Nausea Respiratory _______ _____tension

2 arrhythmias; arrest Hypo depression Hypo

Management of severe Hypermagnesemia 10ml of 10% _________ giving slowly _____/______ infusion ________, if above fail.

calcium gluconate Insulin/glucose Dialysis

The symptoms of hypomagnesaemia are very different from those of hypocalcaemia. T/F

F similar

Hypomagnesaemia Hypomagnesaemia can result in cardiac ________ , _______ sensitivity, ________ discomfort, anorexia and neuromuscular sequelae such as ____,______,______,______ etc.

arrhythmias; digoxin Abdominal parasthesia, vertigo, tetany, seizures, irritability

Hypomagnesaemia Severe hypomagnesaemia can lead to ______calcaemia due to decreased _____ release and activity.

hypo PTH

Long term magnesium deficiency may be a risk factor for coronary artery disease. T/F

Some data suggest that reduced magnesium intake is associated with hypertension and insulin resistance. T/F