Patient 1 - A woman with numbness of hands and feet

A 24 year-old Malawian woman was admitted to the Department of Medicine of Queen Elizabeth Central Hospital in January 2002 with the complaint of: intermittent numbness of hands and feet and sometimes of the lips, over a period of 5 months, and of: stiff and painful hands for 2 days prior to presentation. Systemic inquiry revealed heart palpitations, dizziness, easy fatigability and intermittent episodes of diarrhoea over the same period of time.

Her symptoms started after the birth of her third child by uncomplicated vaginal delivery in a hospital. She was a housewife with no significant previous medical or surgical history. During the time of her illness, she had taken courses of penicillin, co-trimoxazole and paracetamol. She had no known drug allergy.

Examination revealed a woman of good nutritional status, apyrexial, without pallor, jaundice or cyanosis, and with no signs of immunosuppression. She looked weak and was slow in all her movements. The pulse rate was 62/min (regular), breathing 18/min, temperature 36°C, BP 124/70 mmHg.

While the blood pressure was being taken in her right arm, the right hand became stiff, with flexion at the wrist and extension of the fingers (see figures)

1. What condition does this woman have?

2. What are the possible causes of this condition?

3. What investigations must be done to reach to a definitive diagnosis?

Discussion

This woman has tetany, characterised by episodic numbness or paraesthesiae of the hands, feet and lips, sometimes with stiffness or cramps. She has a positive Trousseau's sign, with typical stiff posturing of the hand after inflation of a pressurised cuff to the upper arm, and maintaining the pressure above the systolic level for a few minutes. Important causes of tetany are hypocalcaemia and alkalosis, and management requires seeking which of these is the cause, and what underlying disease is responsible for the biochemical disorder.

A feature that can sometimes be found (but was absent in this patient) is Chvostek's sign - muscular contractions at the corners of the eyes or mouth induced when the facial nerve is lightly tapped with a finger or reflex hammer, just anterior to the parotid gland.

The commonest cause of alkalotic tetany is over breathing (often through anxiety or hysteria). There was no evidence of this in this patient.

Initial investigations were done with the following results:

Full blood count	normal
Red cell morphology	normal
Plasma:
Sodium	138	(135 – 145) mmol/L
Chloride	100	(98 – 106) mmol/L
Potassium	3.6	(3.5 – 5.0) mmol/L
Calcium	5.0	(8.5 – 10.5) mg/dl
Phosphate	9.5	(3.0 – 4.5) mg/dl
Electrocardiogram findings --		Sinus rhythm
		Rate 58 beats per minute,
		regular Prolonged QT
		interval (0.48 sec)
		U waves

The findings (biochemical studies and ECG) confirmed a diagnosis of hypocalcaemia. Other notable findings were the high plasma phosphate concentration and bradycardia. We considered the following possible causes of hypocalcaemia:

1. Renal insufficiency - this is the commonest cause

2. Hypoalbuminaemia - each g/L decrease in serum albumin decreases serum Ca⁺⁺ by 0.8 mg/dl.

3. Hypoparathyroidism and pseudoohypoparathyroidism

4. Hypomagnesaemia

5. Vitamin D deficiency

6. Other causes: pancreatitis, sepsis, massive transfusion of citrated blood and also iatrogenic in cases of post surgery.

Further investigation of plasma samples revealed:

creatinine	1.1	(normal range 0.5 – 1.5) mg/dl
urea nitrogen	22.3	(8 – 25) mg/dl
total protein	7.0	(6.0 – 8.0) g/dl
albumin	4.8	(3.5 – 5.0) g/dl
magnesium	2.0	1.6 – 2.3) mg/gl
parathormone	0.3	(1.1 – 7.7) pmol/L
TSH	9.6	(0.4 – 6.2) mIU/L
T3	0.14	(0.69 – 2.02) ng/ml
T4	2.80	(4.8 – 11.8) ug/dl

X-rays of spine and hands: normal.

These results indicate a diagnosis of primary hypoparathyroidism as the cause of her hypocalcaemia, and the findings also indicate the presence of primary hypothyriodism.

The commonest cause of hypoparathyroidism is surgery - inadvertent removal of the parathyroid glands during operation for goitre or thyrotoxicosis. There was no history of surgery in this patient. Primary hypoparathyroidism is an uncommon cause of hypocalcaemia. Primary hypoparathyroidism may be associated with autoimmune conditions like pernicious anaemia, hypothyroidism, adrenal failure etc. In her case primary hypothyroidism was also found to be present: we had not suspected this clinically, but it is the likely explanation for her slowness of movements and her bradycardia.

This combination of endocrine deficiencies suggests a diagnosis of polyglandular deficiency. Patients with a suspected endocrine derangement need to be fully investigated both for the particular gland and for the other endocrine glands.

The patient was prescribed combined Calcium and Vitamin D₃ supplements and thyroxine tablets, and will be reviewed regularly as an outpatient.

Fig 1.

Patient's arm before application of blood-pressure cuff

Fig. 2.

after application of cuff for about 2 minutes