Quiz 1: Ranges

Question 1

Sodium: Clinical implication, normal range, crit. values, normal urine, renal threshold, Specimen type

Answer 1

Amount of sodium is a reflection of the balance between amount taken in and amount excreted
Normal range = 136- 145 mM or mEq/l,
Critical values: 160 mM
Normal urine = 40- 220mM
Renal threshold = 120 +/- 10mM (above this means all is excreted; below this means it is retained)
CSF = approx.same as serum values for Na
Acceptable specimens: serum, heparinized plasma (Mild Hemolysis is acceptable since not much Na+ is in the cell (extracellular ion))

Question 2

Potassium: Clinical implication, normal range, crit. values, normal urine, renal threshold, Specimen type

Answer 2

Low & high K in cardiac patients may lead to cardiac arrhythmias and heart attack, and requires monitoring.
Normal: 3.5-5.1 mmol/L or mEq/L
Critical: 6.5 mM or mEq/L
Normal urine: 80-90% of daily intake
Renal threshold: none
CSF: 70% of plasma
Hemolyzed sample should be avoided: slight hemolysis can falsely elevate results. Intracellular K+ is much greater than plasma K+.
Muscular activity (fist clenching during phlebotomy) can increase value by 20%

Question 3

Chloride Ranges

Answer 3

• Normal Cl = 98-107 mEq/L
• Normal Urine: 110-250mmol/24hrs
Important in the differential diagnosis of metabolic alkalosis
- Decreased Cl excretion (less than 15 mmol/24hr)

Question 4

Bicarbonate Ranges

Answer 4

Normal = 22-26mmol/L
• Buffering system to maintain physiological normal pH (7.35-7.45)
• pH= pka + log HCO3- H2CO3
• The maximum buffer capacity of bicarbonate-carbonic acid system at pH of 7.4 is at a ratio of 20:1. This is maintained by the lungs which expels CO2.

Question 5

Creatinine Ranges

Answer 5

• Reference range: 0.6-1.5 mg/dL
• Critical range: > 2.0 mg/dL
• May be ordered, along with BUN and/or microalbumin for known renal patients or to monitor drug therapies.
• Levels may also reflect muscle injury.

Question 6

BUN Ranges

Answer 6

• Reference range: 6-20 mg/dL
• Critical range: >40mg/dL
• Increased BUN suggests impaired renal function from (kidney disease, decreased blood flow to kidneys from heart failure, shock, stress, obstruction or dehydration, increased protein catabolism, bleeding, pregnancy.
• If one kidney is fully functioning, a normal serum BUN may result.