MLS 4410 Clinical Chemistry Exam 1

135-145 mmol/L

Reference Range for Na+ in serum/plasma

3.5-5.1 mmol/L

Reference Range for K+ in serum/plasma

98-107 mmol/L

Reference Range for Cl- in serum/plasma

22-26 mmol/L

Reference Range for HCO3- in serum/plasma

23-27 mmol/L

Reference Range for TCO2 in arterial blood and venous blood

8.6-10.0 mg/dL

Reference Range for total Ca2+ in serum/plasma in mg/dL?

0.5-1.00 mmol/L

Reference Range for Mg+ in serum/plasma in mmol/L?

1.3-2.1 mg/dL

Reference Range for Mg+ in serum/plasma in mg/dL?

0.81-1.45 mmol/L

Reference Range for inorganic phosphorus in serum/plasma mmol/L

2.5-4.5 mg/dL

Reference Range for inorganic phosphorus in serum/plasma mg/dL

7.35-7.45

reference range for pH in blood

35-45 mmHg

Reference range for pCO2 in arterial blood

85-105 mmHg

Reference range for pO2 in arterial blood

>95%

Reference range for sO2 in arterial blood

+/- 2

Reference range for base excess

>95%

Reference range for O2Hb in arterial blood

Critical High/Low values for Na+

Critical High/Low values for K+

-Na+

-K+

-Cl-

-HCO3-

Which electrolytes make up the standard panel?

Na+

What is the major extracellular cation

True

The Na+/K+ pump removes 3 Na+ and brings 2 K+ into the cell. True/False

responds to expanded ECF by increasing renal excretion

What is the role of atrial natriuretic peptide?

promotes Na+ reabsorption and K+ excretion in response to low blood pressure/volume.

What is the role of aldosterone?

-ascending loop of Henle

-distal tubule

Where is sodium reabsorbed as a result of aldosterone stimulation?

cellular swelling

What happens to cells when a patient is hyponatremic?

cellular shrinkage

What happens to cells when a patient is hypernatremic?

A false decrease in sodium due to increased lipids/proteins in the plasma.

What is pseudohyponatremia?

Because the ISE analyzer is calibrated to determine sodium levels in plasma that contains 93% water, increased lipids or proteins will skew the reading.

Why is the HIL measurement important in determining sodium levels?

-GI tract involvement

-Neurological involvement (headache, seizures, coma)

What are the symptoms of hyponatremia?

CNS involvement (lethargy, irritability, nausea, vomiting)

What are the symptoms of hypernatremia?

False

IV fluid contamination through the blood draw is a typical cause of false elevation in sodium levels. True/False

K+

What is the major intracellular fluid cation?

2%

What percentage of the body's potassium is free in plasma?

K+

Which electrolyte functions are important in neuromuscular cells, heart muscle contraction, and muscular excitability?

Fluid loss triggers the production of aldosterone, which works to excrete K+

Why does fluid loss result in hypokalemia?

Cushing's syndrome

a condition that increases K+ excretion due to increased levels of cortisol

Hypokalemia. Insulin facilitates the intake of K+ into cells, causing a reduction in the K+ osmolality of the extracellular fluid.

Does insulin overdose cause hypokalemia or hyperkalemia?

hydrogen move from inside the cell to outside the cell.

In alkalosis, which direction to hydrogen ions move across the cell membrane?

Hypokalemia. Because the pH is alkaline, H+ ions exit cells to lower the pH. To maintain electrical neutrality, K+ moves into the cell to compensate the H+ loss, reducing the K+ osmolality of the plasma.

Alkalosis causes hypokalemia or hyperkalemia?

Addison's disease

a condition that contributes to hyperkalemia via reduced aldosterone production

-false increase in potassium

-false decrease in calcium

What two levels will be affected if K2EDTA contamination is suspected? Will they be increased or decreased?

True

Conditions that affect K+ will usually affect Mg+. True/False

intracellular cation

Is Mg+ an IC or EC ion?

extracellular

Is Cl- an IC or EC ion?

HCO3-

Which electrolyte will Cl- move against to maintain neutral charge?

Cl-. Na+ reabsorption is limited by the amount of Cl- available.

Na+ can only be reabsorbed into the proximal tubules in the presence of what other electrolyte?

Diagnosis of cystic fibrosis

What is the purpose of the sweat test?

increased

In cystic fibrosis Cl- concentration in sweat is increased/decreased.

tCO2

What measurement is reflective of 90% of total plasma HC03-

buffering pH

Bicarb's ability to accept a hydrogen ions makes it efficient at what?

carbonic anhydrase

What enzyme is present in renal tubular cells, and is required by the kidneys for regulation of HC03-?

10-20 mmol/L

reference range of anion gap with K+

8-16 mmol/L

reference range of anion gap without K+

1%

What percentage of calcium is found in extracellular fluids?

50%

what percentage of extracellular calcium is ionized?

45%

What percentage of extracellular calcium is bound to proteins?

5%

what percentage of extracellular calcium is complex to anions?

ionized calcium (iCa)

What form of calcium is physiologically active in the body?

True

Total calcium is influenced by total protein and albumin, but iCa is not. True/False.

-Small intestine

-liver

-kidneys

-skin

-skeleton

-parathyroid glands

What are the primary organs involved in calcium homeostasis? (6)

-parathyroid hormone (PTH)

-Vitamin D (calcitriol)

Calcitonin

What are the three regulatory hormones for calcium?

1,25-dihydroxy-vitamin-D

What is the active form of Vitamin D (calcitriol)

25-hydroxy-vitamin D (calcidiol)

What is the inactive form of Vitamin D?

1-alpha-hydroxylase

Which enzyme activation is stimulated by PTH, and is used to convert vitamin D to the active form?

parathyroid gland

Where is PTH secreted from?

decreased levels of free calcium

What stimulates the release of PTH?

-bone reabsorption (release calcium and phosphate)

-renal reabsorption of calcium and secretion of phosphate

-renal activation of Vitamin D

What are three primary actions that result from the release of PTH?

Ingested from fortified foods

What is the source of vitamin D2 in the body?

synthesized in the body via sunlight exposure

What is the source of Vitamin D3 in the body?

Vitamin D3

Cholecalciferol AKA

cholesterol

What is required to synthesize Vitamin D3 in the skin?

liver

What organ is responsible for the activation of 25-dihydroxy-vitamin-D from vitamin D3?

Vitamin D2

Ergocalciferol AKA

kidneys

What organ is responsible for the activation of 25-dihydroxy-vitamin-D from vitamin D2?

-increased absorption of calcium and phosphate from GI tract

-increased bone reabsorption

-enhances PTH role in renal reabsorption of calcium

-stimulates osteoclasts to metabolize bone calcium

What are the roles of vitamin D in its active form? (4)

What values indicate vitamin D deficiency?

21-29 ng/mL of 25-hydroxyvitamin D

What values indicate a vitamin D insufficiency?

thyroid gland

Where is calcitonin secreted?

-inhibits PTH

-inhibits vitamin D

-inhibits bone reabsoption

What are the primary effects of calcitonin? (3)

Mg+

What electrolyte is required for the production and release of PTH?

-muscle cramps

-seizures

-tetany

-cardiac arrhythmias

What are symptoms of hypocalcemia?

Rickets

a disease characterised by the failure to properly mineralize bone in adolescents

Osteomalacia

A disease characterized by inadequate of delayed mineralization of bone, associated with adults

Excess H+ ions compete with Ca2+ for binding sites on albumin, causing an increase of free calcium in the plasma

How does acidosis contribute to hypercalcemia?

Low:

What are the high and low critical values for total calcium?

False. It is distributed equally intracellularly and extracellularly

Phosphorous is an intracellular electrolyte. True/False

increases renal excretion

What is the effect of PTH on phosphorus?

Increases renal and GI absorption of phosphorus

What is the effect of Vitamin D on phosphorus?

phosphorus (values tend to be lower in the morning and higher in the evening)

Which electrolyte exhibits diurnal variation?

UV absorption at 340 nm OR 600-700 nm depending on the method

How is phosphorus measured?

-colorimetric

-atomic absorption spectrophotometry

What two methods or used to measure total calcium?

Mg+

What is the second most abundant intracellular cation?

bone, muscle, soft tissue

Where is magnesium found in highest concentrations in the body?

1%

What percentage of total Mg+ is within RBCs?

-cofactor for utilization of ATP

-membrane stabilization

-nerve conduction

-potassium balance

What are the four main functions of magnesium?

enhances renal reabsorption of Mg+

What effect PTH have on magnesium?

colorimetric

How is Mg+ detected in the lab?

pKa

This value represents the strength of a solution's ability to donate a hydrogen proton

pH = pKa + log([base]/[acid])

write out the Henderson-Hasselbach equation

20:1

What is the normal ratio of bicarbonate to carbonic acid in the blood?