Phosphates and Lactate (FSKP)

Question 0

% phosphate in bone, in soft tissues and in serum/plasma (active form)

Answer 0

80% in bone, 20% in soft tissues, <1% in serum/plasma

Question 1

Predominant intracellular anion

Answer 1

Phosphate

Question 2

Concentration of phosphate in blood

Answer 2

12 mg/dL (3.9 mmol/L)

Question 3

Concentration of inorganic phosphates in blood

Answer 3

3-4 mg/dL

Question 4

complex phosphodiesters

Answer 4

DNA and RNA

Question 5

Coenzymes of phosphates

Answer 5

Esters of phosphoric or pyrophosphoric acid

Question 6

Reservoirs of energy (phosphate)

Answer 6

ATP, creatine phosphate and phosphoenolpyruvate

Question 7

Facilitates release of O2

Answer 7

2,3-biphosphoglycerate (2,3-BPG) in RBcs

Question 8

-Acts to increase Phosphate in the blood

Answer 8

Vitamin D (increased)

Question 9

-Increases both phosphate absorption in the intestine and phosphate reabsorption in the kidney

Answer 9

Vitamin D (increased)

Question 10

In excessive secretion or administration of this, phosphate in the blood may increase because of decreased renal excretion

Answer 10

Growth hormone (increased)

Question 11

Decreases phosphate by inhibiting reabsorption

Answer 11

PTH and calcitonin

Question 12

60-80% of patients in ICU with hypophosphatemia has

Answer 12

Sepsis

Question 13

Causes of hypophosphatemia

Answer 13

• increased renal excretion
• hyperparathyroidism
• decreased intestinal absorption, as w/ vit. D deficiency or antacid use

Question 14

Mortality rate of mild hypophosphatemia

Answer 14

15%

Question 15

Mortality rate of severe hypophosphatemia

Answer 15

<1.0 g/dL or 0.3 mmol/L

30%

Question 16

Causes of hyperphosphatemia

Answer 16

• increased intake of phosphate (neonates)
• increased breakdown of cells
• lymphoblastic leukemia

Question 17

Specimen for determination of inorganic phosphate

Answer 17

Serum or Li heparin plasma, urine (24hr)

Question 18

Sources of error of inorganic phosphate

Answer 18

• oxalate, citrate, or EDTA: interfere
• hemolysis: high conc. inside RBCs
• Circadian rhythm: highest in late morning and lowest in the evening

Question 19

Methods (phosphate)

Answer 19

Colorimetry

1. Fiske Subbarow
2. Gomori Modification

Question 20

Formation of an ammonium phosphomolybdate complex (colorless)

Answer 20

Colorimetry

Question 21

Colorimetry is read by

Answer 21

UV absorption at 340 nm or reduced to form molybdenum blue read at 500-700 nm

Question 22

Specimen of this method is precipitated with TCA

Answer 22

Fiske Subbarow

Question 23

This method uses Molybdenum reagent to form heteromolybdenum complex or phosphomolybdate complex

Answer 23

Gomori Modification

Question 24

Reference range of serum/plasma for phosphate in neonates

Answer 24

1.45-2.91 mmol/L (4.5-9.0 mg/dL)

Question 25

Reference range of serum/plasma for phosphate in child

Answer 25

1.45-1.78 mmol/L (4.5-5.5 mg/dL)

Question 26

Reference range of serum/plasma for phosphate in adults

Answer 26

0.87-1.45 mmol/L (2.7-4.5 mg/dL)

Question 27

Reference range of 24 hr urine for phosphate

Answer 27

13-42 mmol/day (0.4-1.3 g/day)

Question 28

By-product of an emergency mechanism producing a small amount of ATP when O2 delivery is severely diminished

Answer 28

Lactate

Question 29

The normal end product of glucose metabolism (glycolysis)

Answer 29

Pyruvate

Question 30

Conversion of pyruvate to lactate is activated when

Answer 30

A deficiency of oxygen leads to an accumulation of excess NADH

Question 31

Associated with hypoxic conditions (shock, myocardial infarction, severe blood loss)

Answer 31

Type A lactic acidosis

Question 32

Metabolic origin (diabetes mellitus, severe infection, leukemia, liver or renal disease, and toxins [ethanol, methanol, salicylate poisoning])

Answer 32

Type B lactic acidosis

Question 33

Specimen for determination of lactate

Answer 33

• tourniquet should not be used: venous stasis will increase lactate levels
• do not exercise the hand
• anaerobic glycolysis should be prevented
• heparinized blood may be used: must be delivered on ice and plasma must be quickly separated
• use iodoacetate or fluoride to inhibit glycolysis w/o affecting coag

Question 34

Methods (lactate)

Answer 34

Monitoring oxygenation
Enzymatic method (coupled)

Question 35

Enzymatic method (coupled)

Answer 35

Lactae + oxygen (acted by the enzyme: lactate oxidase)—-> pyruvate + hydrogen peroxide (H2O2)

Hydogen peroxide + H donor + chromogen (acted by the enzyme: peroxidase) —-> colored dye + 2 water (H2O)

Question 36

Reference Range of lactate (venous)

Answer 36

0.5-2.2 mmol/L (4.5-19.8 mg/dL)

Question 37

Reference range of lactate (arterial)

Answer 37

0.5-1.6 mmol/L (4.5-14.4 mg/dL)

Question 38

Reference range of lactate (CSF)

Answer 38

1.1-2.4 mmol/L (10-22 mg/dL)

Question 39

Monitoring oxygenation

Answer 39

• in dwelling catethers that measure blood flow
• pulse oximeters
• base-excess determination
• measurements of oxygen consumption (VO2)