Evaluation of a calcium, magnesium and phosphate clinical ordering tool in the emergency department.

OBJECTIVE: We developed a clinical tool comprising patient risk factors for having an abnormal calcium (Ca), magnesium (Mg) or phosphate (PO4) level. We hypothesized that patients without a risk factor do not require testing. This study examined the tool's potential utility for rationalizing Ca, Mg and PO4 ordering in the emergency department (ED). METHODS: We undertook a retrospective observational study in a single metropolitan ED. Patients aged 18 years or more who presented between July and December 2019 were included if they had a Ca, Mg or PO4 test during their ED stay. Demographic and clinical data, including the presence of risk factors, were extracted from the medical record. The primary outcome was a clinically significant abnormal Ca, Mg or PO4 level (>0.2 mmol/l above or below the laboratory reference range). RESULTS: Calcium, Mg and PO4 levels were measured on 1426, 1296 and 1099 patients, respectively. The positive and negative predictive values and likelihood ratios of the tool identifying a patient with a Ca level > 0.2 mmol/l outside the range were 0.05, 0.99, 1.59 and 0.41, respectively. The values for Mg were 0.02, 1.00, 1.44 and 0.35 and those for PO4 were 0.15, 0.93, 1.38 and 0.57, respectively. The majority of patients not identified as having an abnormal level did not receive electrolyte correction treatment. Application of the tool would have resulted in a 35.8% cost reduction. CONCLUSION: The tool failed to predict a very small proportion of patients (approximately 1%) with an abnormal Ca or Mg level and for whom it would have been desirable to have these levels measured. It may help rationalize Ca and Mg ordering and reduce laboratory costs.

Ptaquiloside in bracken spores from Britain.

Secondary metabolites from bracken fern (Pteridium aquilinum (L.) Kuhn) are suspected of causing cancer in humans. The main carcinogen is the highly water-soluble norsesquiterpene glucoside ptaquiloside, which may be ingested by humans through food, e.g. via contaminated water, meat or milk. It has been postulated that carcinogens could also be ingested through breathing air containing bracken spores. Ptaquiloside has not previously been identified in bracken spores. The aim of the study was to determine whether ptaquiloside is present in bracken spores, and if so, to estimate its content in a collection of spores from Britain. Ptaquiloside was present in all samples, with a maximum of 29 µg g(-1), which is very low compared to other parts of the fern. Considering the low abundance of spores in breathing air under normal conditions, this exposure route is likely to be secondary to milk or drinking water.

Gametophyte morphology and ultrastructure of the extremely deep shade fern, Trichomanes speciosum.

• The extent to which macro- and micromorphological features might contribute to tolerance of extremely deep shade by Trichomanes speciosum, a member of the filmy ferns (Hymenophyllaceae), is reported here. • Confocal laser scanning, transmission and scanning electron microscopy were used to study the ultrastructure of gametophytes and sporophyte leaves. • Gametophyte filament cells contain numerous small, spherical or ovoid chloroplasts, whereas sporophyte leaf cells have fewer, slightly larger, disc-shaped chloroplasts. The chloroplast grana of gametophytic cells have fewer thylakoids than sporophyte cells, although grana are not numerous in either. Gametophyte filament cell walls resemble those of sporophyte leaf cells, with two or more layers of electron-opaque material and covered in a thin cuticle. Gemma cell wall ultrastructure does not differ from that of gametophyte filament cells; rhizoid cell walls are thick and several-layered. • Neither gametophyte filaments nor sporophyte leaves have chloroplasts of the extreme forms reported for deep shade fern or angiosperm leaves. The success of the fern is attributed to a low metabolic rate and inability of other species to cope with extreme low light.