Reference intervals for plasma ß-CTX and P1NP in children: A systematic review and pooled estimates.

OBJECTIVE: Reference intervals for plasma P1NP and ß-CTX in children and adolescents from several studies have recently been published. The aim of this study was to combine the available data into a set of reference intervals for use in clinical laboratories. DESIGN AND METHODS: A systematic literature search for primary studies reporting reference intervals for plasma P1NP and ß-CTX in infants, children and adolescents using the Roche methods was carried out. Reference limits were extracted. For each year of age, mean upper and lower reference limits were calculated, weighted by the number of subjects in each study, and were plotted against age. Proposed reference limits were developed from the weighted mean data with age partitions determined pragmatically. RESULTS: Reference limits for clinical use for females to 25 years and males to 18 years, based on the weighted mean reference data, are presented. Ten studies contributed to the pooled analysis. The proposed reference limits are identical for males and females <9 years age, prior to the pubertal growth spurt. For ß-CTX, the weighted mean reference limits showed relatively constant values during the pre-pubertal years but a marked increase during puberty before a rapid decline towards adult values. Those for P1NP showed high values declining rapidly in the first 2 years of life, followed by a modest increase during early puberty. Limited published information for late adolescent and young adult subjects was noted. CONCLUSIONS: The proposed reference intervals may be useful for clinical laboratories reporting these bone turnover markers measured by the Roche assays.

Relationship between testosterone, sex hormone binding globulin and plasma amyloid beta peptide 40 in older men with subjective memory loss or dementia.

In a group of 28 older men with either subjective memory loss or dementia, serum total testosterone and sex hormone binding globulin (SHBG) correlated inversely with plasma levels of amyloid beta peptide 40 (Abeta40, r=-0.5, P=0.01 and r=-0.4, P=0.04, respectively). Calculated free testosterone was also inversely correlated (r=-0.4, P=0.03), and all three relationships remained statistically significant after allowing for age. A similar but non-significant trend was seen with dehydroepiandrosterone sulphate (DHEAS), and neither luteinising hormone (LH) nor estradiol correlated with Abeta40. These data demonstrate that lower androgen levels are associated with increased plasma Abeta40 in older men with memory loss or dementia, suggesting that subclinical androgen deficiency enhances the expression of Alzheimer's disease-related peptides in vivo. An inverse correlation exists between SHBG and Abeta40, warranting further investigation.

An aid to blind nasal intubation.

Blind nasal intubation remains an important technique in the management of the difficult airway. Many aids to this technique have been described, but unfortunately, these often require additional expense, training, and equipment. Methods that involve listening at the end of the endotracheal tube and observing moisture condensation in the tube are relatively insensitive and may expose the operator to the patient's bodily fluids. Our aim was to devise an aid to blind nasal intubation that was effective, inexpensive, simple to learn, and easy to assemble. It is essential that breath sounds can be monitored through the endotracheal tube, as it is felt that this helps to minimize retropharyngeal perforation caused by the tube abutting the posterior pharyngeal wall. We describe the use of an endotracheal tube stethoscope in conjunction with either 'inline' or 'sidestream' capnometry and present a case of successful nasotracheal intubation using this device. The total cost of this aid is less than $10 Australian.