Chloride & Calcium

CHLORIDE (Cl- )

• It is the major extracellular anion

• chief counter ion of Na in ECF

CHLORIDE (Cl- )

• ___ shifts secondarily to Na+ or HCO3-

• It is mainly involved in maintaining osmolality, blood volume, and electroneutrality

• Only known anion to serve as an enzyme activator (Amylase)

Urine & sweat

Excess Cl- is excreted in ___ & ____

aldosterone secretion

In chloride, Excessive sweating stimulates ___

glomerulus,, proximal tubules

How it maintains electroneutrality:

I. Cl- is filtered out by the ________ and passively reabsorbed in conjunction with Na+ by the ____

Chloride shift

REGULATION

II. ________________

— Uptake of Cl- in exchange of HCO3- in red blood cells.

Hyperchloremia

- Dehydration

- Hyperventilation (Respiratory Alkalosis)

- Renal Tubular Acidosis

- Metabolic Acidosis

- Diabetes Insipidus

-Salicylate Intoxication

- GI loss of HCO3- (severe/prolonged diarrhea)

Hypochloremia

- Prolonged Vomiting

- SevereBurns

- Diabetic Ketoacidosis

- Addison's Disease

- Salt-losing nephritis

- Metabolic Alkalosis

Serum or plasma

What specimen is used in Chloride?

Lithium Heparin

What is the anticoagulant used in Chloride?

Marked hemolysis, due to dilutional effect (false decrease)

What is the possible interference in Chloride and how can it affect the result?

Sweat and urine

What other body fluids can be used as a specimen in chloride?

24-hour collection (refrigerate)

What is the specimen/collection of choice for urine in Chloride?

- Ion selective electrode (ISE)

- Coulometric- Amperometric Titration

- Colorimetric methods

Laboratory Determination in Chloride:

- Schales & Schales Method (Mercuric nitrate Titration Method)

- Zall Color reaction (Whitehorn Titration Method)

Colorimetric methods used in chloride:

Ion Selective Electrode (ISE)

- Routine method in Chloride

- very sensitive & very specific

silver chloride- silver sulfide

Ion exchange membrane with Polycrystalline:

________________________ (Silver Polymeric Membrane)

Coulometric- Amperometric Titration

o Cotlove Chloridometer

o Coulometry: quantity of electricity (in coulombs) needed to convert an analyte to a different oxidation state

oAmperometry: measurement of the current flow produced by an oxidation-reduction reaction

Cotlove Chloridometer

What is the machine used in Coulometric- Amperometric Titration?

Coulometry

quantity of electricity (in coulombs) needed to convert an analyte to a different oxidation state

Amperometry

- measurement of the current flow produced by an oxidation-reduction reaction

- pair of silver electrodes serves as the indicator electrodes

Schales & Schales Method (Mercuric nitrate Titration Method)

Chloride:

- Indicator: Diphenylcarbazone

- Reagent: Mercuric nitrate

- Result/End product: Mercuric Chloride (HgCl2) Blue violet

Diphenylcarbazone

What is the indicator used in Schales & Schales Method (Mercuric nitrate Titration Method)?

Mercuric nitrate

What is the reagent used in Schales & Schales Method (Mercuric nitrate Titration Method)?

Result: Mercuric Chloride (HgCl2)

End product: Blue violet

What is the result/end product used in Schales & Schales Method (Mercuric nitrate Titration Method)?

Zall Color reaction (Whitehorn Titration Method)

- Reagent: Mercuric Thiocyanate

- Result/End product: Reddish complex

Mercuric Thiocyanate

What is the reagent of Zall Color reaction (Whitehorn Titration Method)?

End product: Reddish Ferric thiocyanate

End color: Reddish complex

What is the result/end product of Zall Color reaction (Whitehorn Titration Method)?

98-107 mmol/L

Reference range of chloride in plasma/ serum:

110-250 mmol/d, varies with diet

Reference range of chloride in Urine (24h):

CALCIUM (Ca2+ )

• divalent cation with structural and metabolic roles

• 99% bone, 1% is mostly in the blood and other ECF

45

In calcium, ___% circulates as free Ca 2+ ions (ionized calcium/ ical)

40

In calcium, __% is bound to protein, mostly albumin

15

In calcium, __% is bound to anions (citrate, lactate, phosphate, etc.)

CALCIUM (Ca2+ )

an activator of intracellular signal transduction processes and is essential for DNA and RNA biosynthesis

duodenum and upper jejunum

Calcium is absorbed in the _______and ____ via an active transport process

Ionized calcium

• mean concentration in humans of about 1.18 mmol/L

• a more sensitive and specific marker for Ca 2+ disorders

• decrease in concentration

• cannot be reliably calculated from total Ca 2+ especially in acutely ill individuals

1.18 mmol/L

Ionized calcium have a mean concentration in humans of about ___

myocardial function

decrease in concentration of ionized calcium impairs ___

Tenany

decrease in concentration of ionized calcium can cause neuromuscular irritability, which may become clinically apparent as __________ (irregular muscle spasms)

Ionized calcium

• binds to negatively charged sites on the protein molecules

• binding is pH dependent

pH dependent

Binding in ionized calcium is ___

Alkalosis

____________ promotes increased protein binding: decreases ionized calcium

Acidosis

____________ decreases protein binding: increases ionized calcium

Parathyroid hormone

• stimulated by a decrease in ionized Ca 2+

• Bone: bone resorption

• Kidneys: increasing tubular reabsorption of Ca 2+ ions, stimulates renal production of active vitamin D

Vitamin D3

• 1,25-dihydroxycholecalciferol (1,25-[OH]2 -D3) biologically active form

• increases Ca 2+ absorption in the intestine and enhances the effect of PTH on bone resorption

1,25-dihydroxycholecalciferol (1,25-[OH]2 -D3)

biologically active form in Vitamin D3

Calcitonin

• originates in the medullary cells of the thyroid gland

• decrease calcium levels by inhibiting the actions of both PTH and vitamin D

• secreted only in response to a hypercalcemic stimulus

9.0-10.1 mg/dL (2.24-2.53 mmol/L)

Reference range of Total calcium (adults), serum/plasma:

4.6-5.3 mg/dL (1.15-1.33 mmol/L)

Reference range of Ionized (free) calcium, serum:

4.6-5.1 mg/dL (1.15-1.27 mmol/L)

Reference range of Ionized (free) calcium, WB:

Hypocalcemia

decreased calcium level in the blood

Hypocalcemia

- Primary hypoparathyroidismglandular aplasia, destruction, or removal

- Vitamin D deficiency

- Pseudohypoparathyroidism

- Hypomagnesemia

- Rhabdomyolysis

- Acute pancreatitis

- Renal disease

- Hypermagnesemia

Ionized calcium

This is requested for ICU patients or sepsis

Surgery and intensive care

Hypocalcemia occurs commonly in critically ill patients—that is, those with sepsis, thermal burns, renal failure, or cardiopulmonary insufficiency

Hypocalcemia

occurs commonly in critically ill patients—that is, those with sepsis, thermal burns, renal failure, or cardiopulmonary insufficiency

Neonates

• Ionized Ca 2+ concentrations are high at birth and rapidly decline by 10% to 20% after 1 to 3 days

• Child, <3 years old: 2.13-2.63 mmol/ L (8.5-10.5 mg/dL)

10% to 20%

Ionized Ca 2+concentrations are high at birth and rapidly decline by ___ to ___ after 1 to 3 days

2.13-2.63 mmol/L (8.5-10.5 mg/dL)

Ionized Ca 2+concentrations of Child, <3 years old

Chvostek and Trosseau sign

- happen when Ca2+ is decreased

• Neuromuscular irritability and cardiac irregularities

• Severe hypocalcemia, in which total Ca 2+ levels are below 1.88 mmol/L (7.5 mg/dL)

< 1.88 mmol/L (7.5 mg/dL)

In Chvostek and Trosseau sign the total Ca2+ levels are ___

Hypercalcemia

abnormal increase of calcium in the bloodstream

Hypercalcemia

- Primary hyperparathyroidism — adenoma or glandular hyperplasia

- Hyperthyroidism

- Increased vitamin D

- Benign familial hypocalciuria

- Malignancy

- Multiple myeloma

- Milk alkali syndrome

- Thiazide diuretics

- Prolonged immobilization

Primary hyperparathyroidism

- adenoma or glandular hyperplasia

- main cause of hypercalcemia

Malignancy

Second cause of hypercalcemia

Neurologic, GI, and renal symptoms

Symptoms when moderate or severe Ca 2+ elevations (2.62 to 3.00 mmol/L [10.5 to 12 mg/dL]) —> panic level/ critical level

2.62-3.00 mmol/L (10.5-12 mg/dL)

What is the range of the panic/ critical level in calcium (fatal to px)?

Asymptomatic

Symptoms of mild hypercalcemia

Serum

What is the preferred specimen for Total calcium?

Citrate, oxalate, EDTA, hemolysis, icterus, lipemia, paraproteins, and magnesium

What are the interferences of calcium in colorimetric methods

serum or lithium heparin plasma

What is the preferred specimen for ionized calcium?

anaerobically,, 4C

In ionized calcium, Specimens should be collected ______________, transported on ice, and stored at ______ to prevent loss of carbon dioxide

Increase the pH

In ionized calcium, the loss of CO2 will ___ of the sample

Lower pH

In ionized calcium, tourniquet left on too long can __________

- Colorimetric method

- Atomic Absorption Spectrometry

Analytic methods of total calcium:

- Orthocresolpthalein complexone (O-CPC)

- use of Arsenazo III dye

Colorimetric methods of total calcium:

Calcium-Cresolphthalein Complex (purple color)

Purple color

What is the end color of Orthocresolphthalein complexone?

580 nm

What is the absorbance of Orthocresolphthalein complexone?

8-hydroxyquinoline

added to reduce interference by magnesium ions

Formula for Corrected Total Calcium

Corrected Total Ca (mg/dL) = measured total Ca2+ + [(normal albumin - px albumin) x0.8]

Arsenazo III dye

- metallochromic indicator

o Ca 2+ is released from its protein carrier and complexes by acidification of the sample

o high specificity for calcium at slightly acidic pH

Calcium-indicator complex

650 nm

Arsenazo dye method absorbance

Atomic Absorption Spectrometry (AAS)

• reference method for total Ca2+

• rarely used in the clinical setting

• technique is difficult for high-volume laboratories

ion-selective electrode (ISE)

Analytic method of Ionized calcium:

Ion Selective Electrode (ISE)

• membranes impregnated with special molecules that selectively, bind Ca 2+ ions

• electric potential develops across the membrane that is proportional to the ionized Ca 2+ concentration