Phosphates and Lactate (FSKP) Flashcards Preview

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Flashcards in Phosphates and Lactate (FSKP) Deck (40):
0

Predominant intracellular anion

Phosphate

1

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

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

2

Concentration of phosphate in blood

12 mg/dL (3.9 mmol/L)

3

Concentration of inorganic phosphates in blood

3-4 mg/dL

4

complex phosphodiesters

DNA and RNA

5

Coenzymes of phosphates

Esters of phosphoric or pyrophosphoric acid

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Reservoirs of energy (phosphate)

ATP, creatine phosphate and phosphoenolpyruvate

7

Facilitates release of O2

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

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-Acts to increase Phosphate in the blood

Vitamin D (increased)

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

Vitamin D (increased)

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

Growth hormone (increased)

11

Decreases phosphate by inhibiting reabsorption

PTH and calcitonin

12

60-80% of patients in ICU with hypophosphatemia has

Sepsis

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Causes of hypophosphatemia

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

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Mortality rate of mild hypophosphatemia

15%

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Mortality rate of severe hypophosphatemia

<1.0 g/dL or 0.3 mmol/L
30%

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Causes of hyperphosphatemia

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

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Specimen for determination of inorganic phosphate

Serum or Li heparin plasma, urine (24hr)

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Sources of error of inorganic phosphate

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

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Methods (phosphate)

Colorimetry
1. Fiske Subbarow
2. Gomori Modification

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Formation of an ammonium phosphomolybdate complex (colorless)

Colorimetry

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Colorimetry is read by

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

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Specimen of this method is precipitated with TCA

Fiske Subbarow

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

Gomori Modification

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Reference range of serum/plasma for phosphate in neonates

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

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Reference range of serum/plasma for phosphate in child

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

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Reference range of serum/plasma for phosphate in adults

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

27

Reference range of 24 hr urine for phosphate

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

28

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

Lactate

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The normal end product of glucose metabolism (glycolysis)

Pyruvate

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Conversion of pyruvate to lactate is activated when

A deficiency of oxygen leads to an accumulation of excess NADH

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

Type A lactic acidosis

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

Type B lactic acidosis

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Specimen for determination of lactate

-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

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Methods (lactate)

Monitoring oxygenation
Enzymatic method (coupled)

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Enzymatic method (coupled)

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)

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Reference Range of lactate (venous)

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

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Reference range of lactate (arterial)

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

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Reference range of lactate (CSF)

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

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Monitoring oxygenation


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