Page 91 - Practical Handout bio 2 mnu 2025_Neat

Level two – Semester 4 - PharmD Biochemistry-II PB-403 (Practical course) 2024/2025

➢ Why is the measurement of urea selected as a
kidney function test?

• Kidney is the main route for urea excretion, urea excretion

involves glomerular filtration, tubular reabsorption (30-

50%), and active secretion.

• Therefore, renal impairment would cause an increased urea

concentration in the blood/plasma.

➢ Lab values:

There are two ways to report urea concentration:
As a whole molecule: Through its nitrogen content:

Blood urea nitrogen (BUN)
Urea

Used in the rest of the world. Used in US and few countries

Total molecular weight MWT of the nitrogen content=

(MWT)= 60 28

BUN is roughly one-half (28/60 or 0.446) of the blood urea.

Reference value: Reference value:

1.8 – 7.1 mmol/L 7 to 20 mg/dL

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