Serum Magnesium Measurements After Parathyroidectomy for Primary Hyperparathyroidism: Should It be Routine?

BACKGROUND: Parathyroidectomy is the treatment of choice in primary hyperparathyroidism (PHPT). Following surgery, significant changes in bone and mineral metabolism may follow, but routine magnesium monitoring is not standard practice. The occurrence of significant clinical events linked to hypomagnesaemia in 3 patients after parathyroidectomy led to our evaluation of magnesium levels after surgery for PHPT. METHODS: Serum magnesium levels before and after parathyroidectomy for PHPT were prospectively evaluated in a single centre over a year. The incidence and severity of hypomagnesaemia and its correlation with other biochemical variables were assessed. RESULTS: A total of 138 patients underwent parathyroidectomy for PHPT. Pre-operative and day 1 post-operative serum magnesium levels were available in 57/138 (41.3%) and 99/138 (71.7%) patients, respectively. Serum magnesium decreased significantly after surgery (mean ± SD of 0.85 ± 0.08 and 0.75 ± 0.11 mmol/L, respectively, p < 0.001). On the day after parathyroidectomy, 31/99 (31.3%) patients had hypomagnesaemia (<0.70 mmol/L); in 3 of whom it was severe (<0.50 mmol/L). Patients with hypomagnesaemia had lower pre-operative magnesium (mean ± SD of 0.78 ± 0.06 and 0.87 ± 0.07 mmol/L, p < 0.001), higher pre-operative calcium [median (IQR) of 2.83 (2.71-2.99) and 2.71 (2.63-2.80) mmol/L, p = 0.001] and higher post-operative calcium [median (IQR) of 2.41 (2.30-2.51) and 2.35 (2.28-2.43) mmol/L, p = 0.046] compared to those with normomagnesaemia. In addition, these patients demonstrated higher drop in calcium levels after surgery (0.44 ± 0.20 and 0.35 ± 0.18 mmol/L, p = 0.033). Magnesium levels after surgery correlated positively with pre-operative magnesium (r = 0.561, p < 0.001) and post-operative PTH (r = 0.210, p = 0.037) and negatively with pre-operative adjusted calcium (r = - 0.389, p < 0.001). CONCLUSIONS: Serum magnesium decreased significantly following parathyroidectomy for PHPT and nearly a third of patients developed post-operative, mostly mild hypomagnesaemia. Whilst routine serum magnesium measurements could facilitate prompt recognition and treatment of this electrolyte disturbance, further research needs to establish the clinical importance of mild hypomagnesaemia in these clinical settings and, if indicated, to devise optimal treatment strategies.

In vivo thermography during small bowel fusion using radiofrequency energy.

BACKGROUND: Radiofrequency-controlled tissue fusion is a novel technology but the associated lateral thermal damage has not been determined. METHODS: Lateral thermal spread of in vivo and ex vivo bowel in a live porcine model fused by radiofrequency energy was evaluated using dynamic infrared thermography and histology. RESULTS: Mean maximum thermal spread measured on histology was <1.2 mm, with no significant difference between thermal spreads for in vivo and ex vivo bowel for radiofrequency energy delivered at 50 V (p = 0.98) and 100 V (p = 0.85). Mean total maximum thermal spread measured by dynamic infrared thermography was <3.9 mm wide on both sides of the instrument with no significant difference between thermal spreads for in vivo and ex vivo bowel for radiofrequency energy delivered at 50 V (p = 0.34) and 100 V (p = 0.19). Fusion quality for in vivo tissue was better when radiofrequency energy was delivered at 100 V compared with 50 V. However, thermal spread measurements and maximum temperatures reached in the tissue were similar in well- and poorly fused bowel. Thermal changes in well-fused bowel were more uniform throughout the different bowel wall layers, whereas in poorly fused tissues, the mucosa did not show thermally induced changes. There were no significant differences between the maximum temperatures detected for in vivo and ex vivo bowel for radiofrequency energy delivered at 50 V (p = 0.25) and 100 V (p = 0.14). CONCLUSIONS: The total thermal changes at both sides of fused bowel are <3.9 mm. The heat sink effect of the application instrument overshadowed any effects of perfusion on limiting thermal spread. Also, using greater amounts of radiofrequency energy at 100 V to achieve better quality fusion does not necessarily increase lateral thermal damage compared with 50 V.

Plain abdominal radiographs: can we interpret them?

INTRODUCTION: Plain abdominal radiographs commonly form a part of medical assessments. Most of these films are interpreted by the clinicians who order them. Interpretation of these films plays an important diagnostic role and, therefore, influences the decision for admission and subsequent management of these patients. The aim of this study was to find out how well doctors in different specialties and grades interpreted plain abdominal radiographs. MATERIALS AND METHODS: A total of 76 doctors from the Departments of Accident & Emergency, Medicine, Surgery and Radiology (17, 32, 23 and 4, respectively) participated in the study which involved giving a diagnosis for each of 14 plain abdominal radiographs (5 'normal' and 9 'abnormal'). They were also asked the upper limit of normal dimensions of small bowel and large bowel. One point was awarded for correctly identifying whether a radiograph was normal/abnormal, 1 point for the correct diagnosis and 1 point for the correct bowel dimensions, giving a total score of 30. RESULTS: Mean scores out of 30 for specialties were as follows: Accident & Emergency 13.1 (range, 2-22), Medicine 11.2 (range, 2-23), Surgery 15.0 (range, 8-24) and Radiology 17.0 (range, 14-20; P = 0.241). Mean scores out of 30 for different grades of doctors were as follows: pre-registration house officers 10.8 (range, 4-20), senior house officers 13.0 (range, 2-22), registrars/staff grades 13.8 (range, 2-23) and consultants 17.3 (range, 12-24; P = 0.028). Fifteen out of 76 (19.7%) doctors correctly identified the upper limit of normal dimension of small bowel; 24 out of 76 (31.6%) correctly identified the upper limit of normal dimension of large bowel. DISCUSSION: The level of seniority positively correlated with skills of plain abdominal radiograph interpretation. A large number of doctors were unable to give the correct upper limit of normal dimensions for small and large bowel. CONCLUSIONS: All doctors could benefit from further training in the interpretation of plain abdominal radiographs. This could perhaps take place as formal teaching sessions and be included in induction programmes. Until then, plain abdominal films should ideally be reported by radiologists where there are clinical uncertainties; important management decisions made by junior doctors based on these films should at least be confirmed with a registrar, if not a consultant.