Cystatin C serum levels in healthy children are related to age, gender and pubertal stage

Background. This study aims to establish age- and gender-specific cystatin C (CysC) reference values for healthy infants, children, and adolescents and to relate them to pubertal stage, height, weight, and body mass index (BMI). Methods. Serum CysC and creatinine levels of 6217 fasting, morning venous blood samples from 2803 healthy participants of the LIFE Child study (age 3 months to 18 years) were analyzed by an immunoassay. Recruitment started in 2011; 1636 participants provided at least one follow-up measurement. Percentiles for CysC were calculated. Age- and gender-related effects of height, weight, BMI, and puberty status were assessed through linear regression models. Results. Over the first 2 years of life, median CysC levels decrease depending on height (ß = − 0.010 mg/l/cm, p < 0.001) and weight (ß = − 0.033 mg/l/kg, p < 0.001) from 1.06 to 0.88 mg/l for males and from 1.04 to 0.87 mg/l for females. Following the second year of age, the levels remain stable for eight years. From 11 to 14 years of age, there is an increase of median CysC levels in males to 0.98 mg/l and a decrease in females to 0.86 mg/l. The change is associated with puberty (ß = 0.105 mg/l/Tanner stage, p < 0.001 in males and ß = − 0.093 mg/l/Tanner stage, p < 0.01 in females) and in males with height (ß = 0.003 mg/l/cm, p < 0.001). Conclusions. CysC levels depend on age, gender, and height, especially during infancy and puberty. We recommend the use of age- and gender-specific reference values for CysC serum levels for estimating kidney function in clinical practice.:1 Contents ........................................................................................................... 1 2 Introduction ...................................................................................................... 2 GFR measurement ............................................................................................. 2 Technically advanced methods ........................................................................ 2 Serum creatinine................................................................................................ 3 Serum Cystatin C............................................................................................... 3 Current state of research..................................................................................... 5 Reference values of Cystatin C ......................................................................... 5 Cystatin C in healthy test persons .................................................................... 6 Validity of Cystatin C for kidney diseases.......................................................... 6 Post-transplant validity of Cystatin C ............................................................... 7 Validity of Cystatin C in extra-renal diseases .................................................... 7 GFR-equations................................................................................................... 8 Confounders ...................................................................................................... 9 Relevance of the topic ......................................................................................... 11 Hypothesis ........................................................................................................... 13 3 Publication – manuscript................................................................................... 14 4 Summary and interpretation ............................................................................. 16 5 References ........................................................................................................ 20 6 Appendix ........................................................................................................... I 7 Description of the own contributions ................................................................ VII 8 Erklärung über die eigenständige Abfassung der Arbeit .................................. VIII 9 Curriculum vitae ................................................................................................ IX 10 Scientific publications and presentations ....................................................... XI 11 Acknowledgements.......................................................................................... XI

Diagnostic and prognostic potential of joint imaging in patients with anti-citrullinated protein antibodies

The introduction of novel therapeutic strategies set new goals for the patients’ outcome, which aims to achieve remission. This goal requires early diagnosis of RA and prompt efficient pharmacotherapy. The introduction of anti-citrullinated protein antibodies (ACPA) two decades ago allowed an earlier RA diagnosis. However, there are indications that ACPA positivity is still associated with higher rates of radiographic damage. As the small joints in hands and feet commonly are the first involved sites of inflammation, the role of different imaging modalities were studied regarding their diagnostic and prognostic impact for assessment of arthritis in RA. Further, ultrasound (US) and radiography were used to study the association between RA-specific antibodies and the occurrence of arthritis and joint damage in systemic lupus erythematosus (SLE). The use of US allows assessment of soft tissue like joint capsules, tendons and bursae. Used for a live scanning, it is easy to detect effusions and edema. Doppler indicates vasoproliferation were inflammation is present. Also, US seems to be more sensitive than radiography to detect minimal structural changes located at bone surfaces. We wanted to investigate whether US findings in a pre-RA stage can predict development of arthritis. Digital X-ray radiogrammetry (DXR) is a technique based on computerized analyses of standard hand radiographs to calculate peripheral bone mineral density (BMD) of the three middle metacarpal bones (DXR-BMD). In order for early treatment decisions, we aimed to study whether changes in DXR-BMD loss after 3 months can predict radiographic damage in early RA. In conclusion, the studies showed that ACPA-positivity is still associated with a higher risk of radiographic damage regardless of early treatment decisions. Therefore, close radiographic monitoring and readiness to intensive treatment is warranted in ACPA-positive patients. This thesis also shows that erosions detected by US in ACPA-positive patients with arthralgia predict development of clinical arthritis. Also, the magnitude of DXR-BMD loss helps identify patients at higher risk for future radiographic damage, and may therefore help to improve early treatment decisions. Finally, US and radiography confirm a higher rate of arthritis and erosions also in SLE patients who are positive for RA-specific antibodies

Serum levels of the soluble urokinase plasminogen activator receptor (suPAR) correlates with disease activity in early rheumatoid arthritis and reflects joint damage over time

Soluble urokinase plasminogen activator receptor (suPAR) is intensively studied as a biomarker of inflammation and disease outcome in various diseases. In rheumatoid arthritis (RA), suPAR have shown an association with inflammation and swollen joints, but data on suPAR in relation to early disease course and disease progression are lacking. This study investigates the potential of suPAR to predict or reflect disease outcome in early RA. Serum suPAR was measured by enzyme-linked immunosorbent assay at disease onset and after 3 and 36 months in 252 patients from a Swedish prospective observational early RA cohort. Levels and changes of suPAR were analyzed in relation to the 28-joint disease activity score (DAS28) and joint damage according to the Larsen score at inclusion and during follow-up. 100 healthy blood donors served as controls. Circulating levels of suPAR were higher in RA patients at all time points as compared to healthy controls. Baseline suPAR was significantly associated with baseline disease activity whereas suPAR levels at 36 months were associated with joint damage at 36 months. No predictive value of suPAR levels or changes in suPAR levels over time were found. In conclusion, suPAR levels associate with disease activity in early untreated RA and reflects joint damage at later stages. Increased suPAR in established RA could indicate patients in need of frequent monitoring of joint status, irrespective of disease activity. In the view of suPAR as a rapidly emerging biomarker, it is important to be aware of its ability to reflect both inflammation and subsequent damage. (Translational Research 2021; 232:142-149)Funding Agencies|Swedish Society of Medicine; Reinhold Sund foundation; King Gustaf V 80-year foundation; Swedish Rheumatism association; Ostergotland county council</p

Rheumatoid arthritis patients with predominantly tender joints rarely achieve clinical remission despite being in ultrasound remission

Objectives. Given that subjective variables might reduce remission by composite DAS (CDAS), the main objectives were to explore whether RA patients with mainly tender vs mainly swollen joints had differences in patient-reported outcome measures (PROMs), clinical or US assessments or in achieving remission defined by CDAS or US. Methods. In a Nordic multicentre study, RA patients initiating tocilizumab were assessed by PROMs, clinical, laboratory and US assessments (36 joints and 4 tendons) at baseline, 4, 12 and 24 weeks. Remission was defined according to clinical disease activity index (CDAI)/Boolean or no Doppler activity present. Tender-swollen joint differences (TSJDs) were calculated. Statistics exploring changes over time/differences between groups included Wilcoxon, Mann-Whitney, Kruskal-Wallis and Spearman tests. Results. One hundred and ten patients were included [mean (S.D.) age 55.6 (12.1) years, RA duration 8.7 (9.5) years]. All PROMs, clinical, laboratory and US scores decreased during follow-up (P 0 had higher PROMs and CDAI (P 0 achieved CDAI/Boolean remission. Conclusion. Patients with more tender than swollen joints scored higher on subjective assessments but had less US synovitis. They seldom achieved CDAS remission despite many being in Doppler remission. If patients with predominantly tender joints do not reach CDAS remission, objective assessments of inflammation should be performed.Peer reviewe

Seasonal variation of blood pressure in children

Seasonal blood pressure (BP) variation is mostly found between the summer and winter months. Guidelines for diagnosis and treatment of hypertension in children have not considered this variation until recently. This review aims to present an overview of seasonal BP variation in childhood along with potential underlying pathophysiological mechanisms and long-term implications as well as conclusions for future studies. In pediatric cohorts, seven studies investigated seasonal changes in BP. These changes amount to 3.4-5.9 mmHg (or 0.5-1.5 mmHg per - 1 °C difference in environmental temperature) in systolic BP with a peak in fall or winter. Potential mechanisms and mediators of seasonal BP variation include sympathetic activation of the nervous system with an increase of urinary and plasma norepinephrine levels in the winter season. Additionally, the physical activity among children and adolescents was inversely correlated with BP levels. Temperature sensitivity of BP and pediatric BP levels predict future systolic BP and target-organ damage. Therefore, cardiovascular events may even be long-term complications of seasonal BP variation in pediatric hypertensive patients. Overall, these data strongly suggest an important effect of ambient temperature on BP in children. Additional studies in pediatric cohorts are needed to define how best to incorporate such variation into clinical practice

Decrease in bone mineral density during three months after diagnosis of early rheumatoid arthritis measured by digital X-ray radiogrammetry predicts radiographic joint damage after one year

BACKGROUND: Periarticular osteopenia is an early sign of incipient joint injury in rheumatoid arthritis (RA), but cannot be accurately quantified using conventional radiography. Digital X-ray radiogrammetry (DXR) is a computerized technique to estimate bone mineral density (BMD) from hand radiographs. The aim of this study was to evaluate whether decrease in BMD of the hands (BMD loss), as determined by DXR 3 months after diagnosis, predicts radiographic joint damage after 1 and 2 years in patients with early RA. METHODS: Patients (n = 176) with early RA (&lt;12 months after onset of symptoms) from three different Swedish rheumatology centers were consecutively included in the study, and 167 of these patients were included in the analysis. Medication was given in accordance with Swedish guidelines, and the patients were followed for 2 years. Rheumatoid factor and antibodies to cyclic citrullinated peptides (anti-CCP) were measured at baseline, and 28-joint Disease Activity Score (DAS28) was assessed at each visit. Radiographs of the hands and feet were obtained at baseline, 3 months (hands only) and 1 and 2 years. Baseline and 1-year and 2-year radiographs were evaluated by the Larsen score. Radiographic progression was defined as a difference in Larsen score above the smallest detectable change. DXR-BMD was measured at baseline and after 3 months. BMD loss was defined as moderate when the decrease in BMD was between 0.25 and 2.5 mg/cm2/month and as severe when the decrease was greater than 2.5 mg/cm2/month. Multivariate regression was applied to test the association between DXR-BMD loss and radiographic damage, including adjustments for possible confounders. RESULTS: DXR-BMD loss during the initial 3 months occurred in 59% of the patients (44% moderate, 15% severe): 32 patients (19%) had radiographic progression at 1 year and 45 (35%) at 2 years. In multiple regression analyses, the magnitude of DXR-BMD loss was significantly associated with increase in Larsen score between baseline and 1 year (p = 0.033, adjusted R-squared = 0.069). CONCLUSION: DXR-BMD loss during the initial 3 months independently predicted radiographic joint damage at 1 year in patients with early RA. Thus, DXR-BMD may be a useful tool to detect ongoing joint damage and thereby to improve individualization of therapy in early RA

Changes in anti-citrullinated protein antibody isotype levels in relation to disease activity and response to treatment in early rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease where serum analysis of anti-citrullinated peptide/protein antibodies (ACPA) is an important diagnostic/prognostic tool. Levels and changes of ACPA in RA patients have been studied previously in relation to disease course and therapy response, but less is known regarding ACPA isotype changes in early RA. Hence, recent-onset RA patients (n = 231) were subjected to a 3-year clinical and radiological follow-up. Serum samples were serially collected and ACPA isotypes were analysed using the second-generation cyclic citrullinated peptide (CCP) as capture antigen. Changes in ACPA isotype levels and status were related to disease course and pharmacotherapy. At inclusion, 74% of the patients tested positive for ACPA IgG; 55% for immunoglobulin (Ig)A, 37% for secretory IgA (SIgA) and 35% for IgM. The proportion of positive patients decreased significantly at follow-up regarding ACPA SIgA, IgM and IgA. During the initial 3 months, reduction of the 28-joint disease activity score (DAS28) correlated with reduced levels of ACPA IgG (Rho = 0 center dot 242, P = 0 center dot 003), IgA (Rho = 0 center dot 260, P = 0 center dot 008), IgM (Rho = 0 center dot 457, P amp;lt; 0 center dot 001) and SIgA (Rho = 0 center dot 402, P amp;lt; 0 center dot 001). Levels of ACPA SIgA (P = 0 center dot 008) and IgM (P = 0 center dot 021) decreased significantly among patients with good response to treatment, which was not seen regarding ACPA IgA or IgG. Changes in ACPA isotype levels were not associated with radiographic damage. In conclusion, ACPA SIgA and IgM declined rapidly upon anti-rheumatic therapy and correlated with decreased disease activity in recent-onset RA. This may indicate that down-regulation of mucosal immunity to citrullinated proteins/peptides and recruitment of new B cells are key features of therapy responses in early RA.Funding Agencies|Swedish Society of Medicine; Swedish research council; Medical research council of south-east Sweden; Reinhold Sund foundation; King Gustaf V 80-year foundation; Swedish rheumatism association; Ostergotland county council</p