This question gets at whether or not you can recognize Trousseau's Sign or Chvostek's Sign in kind of an unusual presentation. Basically you get muscle twitches in the setting of Hypocalcemia. Hypoxemia further exacerbates the sign and can cause twitches randomly throughout the body.

Chvostek's Sign is tapping on the facial nerve of the face that illicits a facial muscle spasm.

Trousseau's Sign is when you put a blood pressure cuff on a patient. This causes cells in the arm to not recieve blood -> No O2 -> No oxidative phosphorylation -> decrease in ATP available -> Na+/K+ pump fails without ATP -> Increased intracellular Na+ -> Increased Ca+ because of increased Na+/Ca2+ exchanger -> decreased SERUM Ca2+ -> Flexion of hand.

Trousseau's Sign is more sensitive for Hypocalcemia, but both are diagnostic. Other tips in this question - Tingling around the mouth, hands, and feet can be another sign of Hypocalcemia. Both generalized tonic-clonic or focal motor seizures can occur with hypocalcemia.

I found an easier way to just logic through this is the complaints are basically muscle spasms, tetany, hyperreflexia.

• Abnormalities in bicarbonate give metabolic acidosis/alkalosis, nothing in stem gives us reason to think theres acid/base balance.
• calcium, hypocalcemia textbook fits with tetany, hyperreflexia
• abnormal chloride not much clinically significant
• potassium abnormalities can have tetany but also arrhythmia, no signs of cardiac involvement
• sodium, hyponatremia can have seizures, hypernatremia have irritability and signs unlikely to be ongoing for entire month.

think of it as this way- he is having GTCT, and then 1 month H/O - pins and needles around mouth - I though calcium problem, and then again he has involuntary muscle contraction.

Hypocalcemia can present with muscular twitching and spams, might cause tetany, and in severe cases lead to seizures like happened in this patient.

This question can be confusing mainly because whenever u think of seizure or neurologic manifestation, you think of Sodium, but the key here is the 1 MONTH history of episodes of pins-and-needles with involuntary contraction of muscles. Also you can rule out Potassium, because although it can cause muscle cramps, spasms and weakness, it leads to cardiac abnormalities (arrhythmias).