The parathyroid glands are small, inconspicuous, and variable in number, colour and position. Their identification is vital for excision of hyper-functioning glands and for preservation of normally functioning ones in patients undergoing thyroidectomy. Intravenous infusion of methylene blue at a dose of 7.5 mg/kg is commonly used to aid visualization of the parathyroid glands intra-operatively. Methylene blue is generally considered benign, and there are only two cases published in the literature reporting toxicity following intravenous infusion--such toxicity is a diagnosis of exclusion. We report a case of methylene blue toxicity resulting in expressive aphasia, confusion and disinhibition following infusion for parathyroid adenoma localization. The patient made a complete recovery over 48 hours. Methaemoglobinaemia was excluded as a cause. We suggest that the mechanism of toxicity was a direct effect of methylene blue, although an adverse interaction with serotonin re-uptake inhibitors could not be excluded. In keeping with the UK National Poisons Information Service recommendations, we have altered our practice and now use methylene blue at a dose not exceeding 4 mg/kg. This has not affected our success rate for identification of parathyroid glands. We report this case to highlight the rare occurrence of methylene blue toxicity when used at a dose of 7.5 mg/kg.

Biochemical parameters will not accurately predict the size of a parathyroid adenoma. The size of a parathyroid adenoma does not correlate with postoperative calcium levels and is therefore not useful as a predictor of postoperative hypocalcaemia.

Summary:Orbital cellulitis and abscess formation are uncommon complications of sinusitis. Early diagnosis and treatment are important to prevent blindness and intracranial complications. We present four consecutive cases referred over 2 years which demonstrate how diagnostic delays may occur and suggest a protocol to avoid similar delays.

Minimal access techniques are increasingly used to remove parathyroid adenomas. Such surgery depends on accurate preoperative localization but the selection of imaging modality remains controversial. We have reviewed the accuracy of ultrasonography, sestamibi scintigraphy and their combination in 48 cases of primary hyperparathyroidism. Ultrasound had a sensitivity of 64.3% (95% confidence interval 44.1-81.4) and positive predictive value (PPV) of 100% (81.5-100) for correct lateralization. Sestamibi had a sensitivity of 83.3% (69.8-92.5) and PPV of 87.1% (73.7-95.1). The simple combination of ultrasound with sestamibi had a sensitivity of 82.1% (63.1-93.9) and a PPV of 92.0% (74.0-99.0): little different from sestamibi alone. However, if the sestamibi result was disregarded in favour of ultrasonography in discordant cases, the sensitivity reached 96.4% (81.7-99.9) and the PPV was 100% (87.2-100). These results were not dependant on a learning curve or the size of adenoma.

Preoperative pamidronate in combination with high doses of oral alfacalcidol and calcium supplements can prevent symptomatic postoperative hypocalcaemia, reduce the requirement for intensive monitoring of calcium, reduce patient morbidity, and reduce hospital stay from 9.2 +/- 1.9 to 5.7 +/- 2.9 days, P < 0.05. However, in the longer term pamidronate may potentially delay bone remodelling.