Endocrine Abstracts

Introduction: The objective of this study is to detect whether the correction of hypomagnesaemia would help to relief the symptoms of hypocalcaemia that occurs after thyroidectomy.

Methods: This prospective study comprised 35 patients who had thyroidectomy between September 2001 and June 2002. Thirteen patients had total thyroidectomy (TT), thirteen had total lobectomy on one side and subtotal lobectomy on the other side (TLSL) and nine patients had hemithyroidectomy. Thyroid functions, calcium, magnesium, albumin and parathormone were checked at initial presentation. After the operation, serum and ionized calcium, serum magnesium, parathormone and albumin were checked daily for five days and longer for patients with hypocalcaemia and hypomagnesaemia.

Results: Of the TT group, seven patients developed hypocalcaemia, five of them showed symptoms of hypocalcaemia. Four of the seven developed hypomagnesaemia as well. Two patients who had TLSL developed hypocalcaemia and hypomagnesaemia and were symptomatic. Another two patients developed hypomagnesaemia only without symptoms. Patients who had both hypocalcaemia and hypomagnesaemia required longer treatment with calcium than those with hypocalcaemia and the symptoms were markedly improved with the administration of magnesium.

Conclusion: Hypocalcaemia was found to be much higher after more radical resection. The presence of hypomagnesaemia renders the symptoms more severe with delay in the response to calcium supplementation. In this case, symptomatic relief of hypocalcaemia needs the correction of both calcium and magnesium.

NOTE: Due to a mistake during production the above abstract, although correct, is not that which was published. The incorrect, published version appears below.

IGF-I is an important measure of disease activity in states of GH deficiency and excess and therefore it is interesting that a significant proportion of AsGHD have normal IGF-I levels. In an attempt to understand the factors determining IGF-I values in patients with severe AGHD we have compared age-, gender- and BMI-matched GHD patients (defined by the international consensus criteria, peak GH <3 ng/ml) with low and IGF-I (Norms: n=5, 3 males, age 42 (31–54), BMI=32.8 (22.4–33.3) kg/m²; Los: n=5, 2 males, age 43 (38–53), BMI 36.5 (30.9–39.9) kg/m²).

Mean GH was calculated from a 24 h profile (20 minute sampling). GH was assessed using a sandwich-type immunoassay (intra- and inter-assay CV <7%, limit of detection 0.1 ng/ml). IGF-I was measured by immunoradiometric assay (sensitivity 4.4–5.2%, specificity of 5.7–7.4%, lower limit of detection 6 mcg/l). Statistical analysis was performed using GraphPad Prism software.

There was no difference between the groups in peak GH during the diagnostic stimulation test (0.3(<0.3–1.2) ng/ml vs 0.3(<0.3–0.8) ng/ml, P=0.84), age of onset (Norms and Los childhood/adult=3/2), prior irradiation status (Norms=3, Lows=2) and current DEXA body composition (total fat 31106(20322–45725) g vs 35548(29159–46072), P=0.22; %trunk fat 33.5(30.4–46.9)% vs 39.2(28.9–42.2)%, P=1; lean mass 50183(46656–66119) g vs 55299(45239–74339) g, P=0.84). However, Los had more other pituitary hormone deficiencies than Norms (3 (1–3) vs 1 (0–1), P=0.03).

Mean 24 h GH tended to be lower in patients with low IGF-I levels (Norms: median 0.1, range <0.1–0.13 ng/ml vs Los: all <0.1 ng/ml, P>0.05).

In conclusion, other than IGF-I levels the only differences between the cohorts were a tendency for more pituitary hormone deficiencies and lower 24 hr GH secretion in those with a low IGF-I. The significance of these observations requires further investigation.