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.

     

Evidence of break-points in breathing pattern at the gas-exchange thresholds during incremental cycling in young, healthy subjects

The present study investigated whether ‘break-points’ in breathing pattern correspond to the first ( G_\textEX1 G_{{{\text{EX}}_{1} }} ) and second gas-exchange thresholds ( G_{\textEX 2} G_{{{\text{EX}}_{ 2} }} ) during incremental cycling. We used polynomial spline smoothing to detect accelerations and decelerations in pulmonary gas-exchange data, which provided an objective means of ‘break-point’ detection without assumption of the number and shape of said ‘break-points’. Twenty-eight recreational cyclists completed the study, with five individuals excluded from analyses due to low signal-to-noise ratios and/or high risk of ‘pseudo-threshold’ detection. In the remaining participants (n = 23), two separate and distinct accelerations in respiratory frequency (f _R) during incremental work were observed, both of which demonstrated trivial biases and reasonably small ±95% limits of agreement (LOA) for the G_\textEX1 G_{{{\text{EX}}_{1} }} (0.2 ± 3.0 ml O₂ kg⁻¹ min⁻¹) and G_{\textEX 2} G_{{{\text{EX}}_{ 2} }} (0.0 ± 2.4 ml O₂ kg⁻¹ min⁻¹), respectively. A plateau in tidal volume (V _T) data near the G_\textEX1 G_{{{\text{EX}}_{1} }} was identified in only 14 individuals, and yielded the most unsatisfactory mean bias ±LOA of all comparisons made (−0.4 ± 5.3 ml O₂ kg⁻¹ min⁻¹). Conversely, 18 individuals displayed V _T-plateau in close proximity to the G_{\textEX 2} G_{{{\text{EX}}_{ 2} }} evidenced by a mean bias ± LOA of 0.1 ± 3.1 ml O₂ kg⁻¹ min⁻¹. Our findings suggest that both accelerations in f _R correspond to the gas-exchange thresholds, and a plateau (or decline) in V _T at the G_{\textEX 2} G_{{{\text{EX}}_{ 2} }} is a common (but not universal) feature of the breathing pattern response to incremental cycling.     

Effect of static wrist position on grip strength

Background:

Grip strength after wrist arthrodesis is reported to be significantly less than normal. One of the reasons suggested for this decrease in grip strength is that the arthrodesis was performed in a suboptimal position. However, there is no consensus on the ideal position of wrist fusion. There is a paucity of studies evaluating the effect of various fixed positions of the wrist on grip strength and therefore, there is no guide regarding the ideal position of wrist fusion. The authors′ aim was to determine the grip strength in various fixed positions of the wrist and subsequently to find out in which position of wrist fusion the grip strength would be maximal.

Materials and Methods:

One hundred healthy adults participated in the study. For the purpose of this study, the authors constructed splints to hold the wrist in five different fixed positions: 45, 30 and 15 degrees of wrist extension, neutral and 30 degrees of wrist flexion. The grip strength in all the participants was measured bilaterally, first without a splint and then with each splint sequentially.

Results:

The average grip strength without the splint was 34.3 kg for right and 32.3 kg for the left hand. Grip strength decreased by 19–25% when the wrist was splinted. The maximum average grip strength with a splint on was recorded at 45 degrees of extension (27.9 kg for right and 26.3 kg for left side). There was a gradual increase in the grip strength with increase in wrist extension but the difference was not statistically significant (P = 0.29). The grip strength was significantly less in flexed position of the wrist (P < 0.001).     

Universal testing and treatment as an HIV prevention strategy: research questions and methods

Achieving high coverage of antiretroviral treatment (ART) in resource-poor settings will become increasingly difficult unless HIV incidence can be reduced substantially. Universal voluntary counselling and testing followed by immediate initiation of ART for all those diagnosed HIV-positive (universal testing and treatment, UTT) has the potential to reduce HIV incidence dramatically but would be very challenging and costly to deliver in the short term. Early modelling work in this field has been criticised for making unduly optimistic assumptions about the uptake and coverage of interventions. In future work, it is important that model parameters are realistic and based where possible on empirical data. Rigorous research evidence is needed before the UTT approach could be considered for wide-scale implementation. This paper reviews the main areas that need to be explored. We consider in turn research questions related to the provision of services for universal testing, services for immediate treatment of HIV-positives and the population-level impact of UTT, and the research methods that could be used to address these questions. Ideally, initial feasibility studies should be carried out to investigate the acceptability, feasibility and uptake of UTT services. If these studies produce promising results, there would be a strong case for a cluster-randomised trial to measure the impact of a UTT intervention on HIV incidence, and we consider the main design features of such a trial.     

Replantation surgery

The current concepts of replantation surgery, a procedure that has been practiced for half a century, can be discussed in terms of patients' demands and expectations, present indications for the procedure, available evidence that influences decision making, and technical refinements practiced to produce better outcomes.     

Revascularization of a finger with a thenar mini-free flap

A devascularized index finger with a soft tissue defect on its palmar side was managed by using a small free flap raised at the level of the metacarpophalangeal joint of the thumb. The radial digital artery was included in the flap and used to revascularize the index finger, and a palmar vein was used to drain the flap. This resulted in minimal donor side morbidity.     

The tumour-suppressor p53 is not required for pancreatic β cell death during diabetes and upon irradiation

Immune-independent diabetes often occurs via pancreatic β cell dysfunction. However, the role of the tumour suppressor p53 that regulates cellular life and death in multiple tissues, in pancreatic cell death and diabetes has not been clarified. We have therefore utilized an established mouse model for diabetes in which the MHC class I antigen is overexpressed in pancreatic β cells under the rat insulin promoter, to investigate the role of p53. We show that pancreatic β cell death, as determined by TUNEL staining, is elevated in transgenic mice compared to wild-type mice. However, there was no increase in immuno-reactivity towards anti-p53 antibodies in the pancreas of transgenic mice over the course of diabetes formation and β cell death, suggesting that p53 may not be involved in these processes. Interestingly, p53 expression was also not induced in pancreas upon γ-irradiation, which resulted in a massive increase in the number of TUNEL-positive cells, suggesting that the p53 pathway may not be causally involved in pancreatic cell death. To further confirm these findings, we generated MHC class I transgenic mice lacking p53 expression. Absence of p53 did not result in any significant changes in pancreatic morphology or affect cell death levels. Importantly, p53 absence did not rescue the diabetic phenotype of the transgenic mice. The results therefore demonstrate that p53 may not be causally involved in pancreatic β cell death, and suggests that the classical cell death pathway dependent on p53 may not be operating in pancreatic β cells.