Determination of the renal concentration capacity following intravenous administration of dDAVP in healthy humans.

The synthetic AVP analogue 1-desamino-8-d-arginine-vasopressin (dDAVP) is used for treatment of polyuric disorders. Lack of commercially available assays limits the usefulness of dDAVP as a diagnostic tool in the assessment of renal concentrating capacity. We aimed to develop a specific radioimmunoassay (RIA) for determination of plasma dDAVP (pdDAVP) in order to investigate the relationship between pdDAVP levels and urine osmolality (Uosm). Further, we aimed to determine the onset, duration, and maximum concentrating capacity following intravenous (i.v.) bolus dDAVP injection. The dDAVP assay was based on a well-established RIA for measurements of AVP. Fourteen healthy subjects (aged 15-18 years) participated. Blood and urine samples were collected prior to and after i.v. bolus of 0.03 µg/kg dDAVP. Diuresis and Uosm was measured for nine hours following dDAVP administration. PdDAVP and Uosm were analyzed.We established a specific RIA for the measurement of pdDAVP. All subjects reached maximal pdDAVP concentration (Cmax) 30 minutes following infusion, and a rise in Uosm after 60 minutes. Maximal Uosm varied between subjects, with no direct correlation to the achieved pdDAVP levels. We found no significant intra-individual variation between two dDAVP infusions and the effect was reproducible in terms of Cmax and maximal Uosm. We characterized the relationship between pdDAVP and Uosm after dDAVP bolus injection in healthy adolescents using our dDAVP assay. Maximal Uosm achieved correlated with the baseline Uosm levels and seemed unrelated to achieved pdDAVP levels. The urine concentrating response was maintained at least eight hours.

Response to Early-onset Pamidronate Treatment in Chronic Nonbacterial Osteomyelitis: A Retrospective Single-center Study.

OBJECTIVES: Chronic nonbacterial osteomyelitis (CNO) is a sterile inflammatory bone disorder with an unpredictable disease course. The objective was to assess clinical and radiological disease activity in children with CNO including response to early-onset pamidronate treatment. METHODS: A single-center retrospective study was conducted of children fulfilling the Bristol Criteria for CNO. At the time of diagnosis, whole-body magnetic resonance imaging (WB-MRI) or local MRI was performed to assess radiological disease activity. Children with multifocal or spinal bone inflammation and clinical disease activity not responding to nonsteroidal antiinflammatory drugs were categorized as having extended CNO. Clinical disease activity was assessed annually. RESULTS: Fifty-one children were included. Median followup time was 4 years (interquartile range 3-7). Children categorized with extended CNO (n = 32) were treated in an early-onset 2-year pamidronate regimen. In extended CNO, WB-MRI was performed at time of diagnosis, and at years 1 and 2 in 88%, 84%, and 91% of cases, respectively. During the first year, the total number of radiologically active lesions and number of spinal lesions per patient declined (p = 0.01). Clinically inactive disease was recorded in 12/32 children (38%). However, 8/12 children (67%) experienced clinical relapse. In limited CNO (n = 19), 10/19 children (53%) presented with clinically inactive disease after 1 year and did not experience clinical relapse. CONCLUSION: Pamidronate might contribute to improvement in clinical and radiological disease activity in extended CNO, especially after 1 year of treatment. However, children with continuously active disease after 2 years of pamidronate treatment were seen.