Question

Normal serum calcium level in cattle is

• A. 5.9-7.1 mg/dl
• B. 8.5-10 mg/dl
• C. 5.9-7.1 g/dl
• D. 8.5-10 g/dl

Hint:

Always pay close attention to the units in biochemistry questions:
- Calcium is measured in mg/dl (milligrams per deciliter).
- Proteins and hemoglobin are measured in g/dl (grams per deciliter).
- Normal calcium = \(8.5-10\) mg/dl.
- Parturient paresis (milk fever) occurs when calcium drops below \(5.5\) mg/dl.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Calcium is a vital divalent cation essential for bone structure, muscle contraction, blood coagulation, and nerve impulse transmission.
Serum calcium levels are tightly regulated within a narrow physiological range to ensure normal neuromuscular function.

Step 2: Detailed Explanation:
The normal serum calcium concentration in healthy adult cattle is approximately 8.5 to 10 mg/dl (equivalent to \(2.1-2.5\) mmol/L).
This level is maintained through the coordinated actions of parathyroid hormone (PTH), calcitriol (active Vitamin D), and calcitonin, which act on the bone, kidneys, and intestines.
Let us analyze the options:
- Option (B) 8.5-10 mg/dl is the correct normal physiological range.
- Option (A) 5.9-7.1 mg/dl represents a hypocalcemic state, which can lead to clinical subclinical parturient paresis (milk fever).
- Options (C) and (D) use the unit g/dl (grams per deciliter).
This unit is incorrect because calcium is present in the blood in milligram quantities.
Grams per deciliter is used for measuring macromolecules like total serum protein or hemoglobin.
A drop in serum calcium below 5.5 mg/dl in peri-parturient cows leads to parturient paresis (milk fever).
This condition is characterized by flaccid paralysis and recumbency due to the blockade of neuromuscular transmission.

Step 3: Final Answer:
The normal serum calcium level in cattle is 8.5-10 mg/dl.