Background Normocalcaemic primary hyperparathyroidism (NPHPT) is often under‐recognised in clinical practice. Aim To determine the prevalence and clinical significance of NPHPT in an unselected sample in an acute hospital setting. Methods Patients aged >18 years who had measurement of an elevated serum parathyroid hormone (PTH ≥ 7 pmol/L) during 12 months from 1 January 2017 to 31 December 2017 were retrospectively studied. NPHPT was defined by the presence of elevated serum PTH with normal albumin‐corrected serum calcium on two or more occasions after excluding secondary causes. Patients were followed up for 2 years. Relevant data were collected by review of electronic medical records. Results Of the 2593 patients who had PTH measured during the study period, 1278 had serum PTH ≥ 7 pmol/L. Hypercalcaemic primary hyperparathyroidism (PHPT) was diagnosed in 174 patients. Secondary causes for elevated serum PTH were identified in 993 patients: 815 (chronic kidney disease – estimated glomerular filtration rate < 60 mL/min/1.73 m2 or renal transplant), 98 (vitamin D deficiency – 25(OH)D < 50 nmol/L), 28 (gastric bypass surgery), 38 (medications), 13 (malabsorption or post‐thyroidectomy) and 1 (hypercalciuria). Data were incomplete for 80 patients. The prevalence of NPHPT with and without the exclusion of hypercalciuria was 0.19% (5) and 0.39% (10) respectively. The prevalence of nephrolithiasis in NPHPT was higher than PHPT (100% vs 15% among five patients (P < 0.001) and 50% vs 15% among 10 patients (P = 0.014)). The prevalence of osteoporosis was not significantly different between NPHPT and PHPT (20% vs 45% among five patients (P = 0.389) and 30% vs 45% among 10 patients (P = 0.518)). Conclusion These findings give further credence to the diagnosis of NPHPT as a clinical entity. Nephrolithiasis may be a greater problem than osteoporosis in NPHPT compared with PHPT. This needs prospective evaluation.

We discuss the case of an 83-year-old man admitted to the hospital after losing control of his vehicle due to an unexplained episode of altered consciousness. This occurred on a background of multiple similar episodes associated with acute confusion, superimposed on a gradual cognitive decline spanning 6 years. Organic aetiologies for delirium were excluded and CT and MRI of the brain were negative for cerebrovascular accidents or other epileptogenic foci. Electroencephalogram (EEG) was negative for epileptiform activity. A diagnosis of seizure in the setting of dementia with Lewy bodies (DLB) was deemed probable. Subsequent brain single-photon emission computed tomography (SPECT) and flurodeoxy glucose-positron emission tomography (FDG-PET) studies supported the underlying diagnosis of DLB. Acute changes in consciousness or cognition are often related to strokes or seizures in the older person. As illustrated in this case, however, it is important to consider alternative comorbidities that may coexist.