Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are markers of inflammatory conditions and have been used extensively by clinicians both in outpatient and inpatient settings. It is important to understand the physiologic principles behind these two tests so clinicians may use them appropriately. For example, fibrinogen (for which ESR is an indirect measure) has a much longer half-life than CRP, making ESR helpful in monitoring chronic inflammatory conditions, whereas CRP is more useful in diagnosis as well as in monitoring responses to therapy in acute inflammatory conditions, such as acute infections. Many factors can result in falsely high or low ESR and CRP levels, and it is important to take note of these. Therefore, if used wisely, ESR and CRP can be complementary to good history taking and physical examination in the diagnosis and monitoring of inflammatory conditions.

Mutations of the Surfactant Protein C (SPC) gene (SFTPC) have been associated with childhood interstitial lung disease (chILD) with variable age of onset, severity of lung disease, and outcomes. We report a novel mutation in SFTPC [c.435G->A, p.(Gln145)] that was associated with onset of symptoms in early infancy, progressive respiratory failure with need for prolonged mechanical ventilatory support, and eventual lung transplant at 1 year of age. While the mutation was not predicted to alter the amino acid sequence of the SP-C precursor protein, analysis of SP-C transcripts demonstrated skipping of exon 4. Because of limited data about the outcomes of infants with SFTPC mutations, we conducted a systematic review of all the SFTPC mutations reported in the literature in order to define their presenting features, clinical and radiologic features, and outcomes. Further advances in our understanding of chILD and creation of an international registry will help to track these patients and their outcomes. Pediatr Pulmonol. 2017;52:57-68. © 2016 Wiley Periodicals, Inc.

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Background: Cherubism, caused by autosomal dominant mutations in the SH3BP2 gene, is characterized by increased bone resorption with development of bilateral fibro-osseous lesions limited to the maxilla and mandible. The SH3BP2 gene is thought to be involved in osteoclastogenesis. Affected children, while usually asymptomatic at birth, typically present at 2–5 years of age with cheek and jaw swelling with upward tilting of eyes due to expansion of fibrous tissues. Bone resorption and proliferation of lesions continues until puberty after which spontaneous regression occurs. RANKL is a cytokine expressed on the surface of osteoclast precursors and is responsible for inducing osteoclast differentiation. Denosumab is an anti-RANKL monoclonal antibody which prevents osteoclast maturation. However, it has a short half-life, and effects on bone turnover have been found to be rapidly reversible after drug discontinuation. The rebound increased bone turnover can lead to severe hypercalcemia. Clinical Case: A 4 year old boy with cherubism (c.1253C>G pathogenic variant in SH3BP2), after failing a 10-month trial of tacrolimus, was placed on monthly denosumab (2 mg/kg) for a total of 10 doses. During denosumab therapy, he received calcium and vitamin D to prevent hypocalcemia; these were stopped once denosumab was discontinued. He presented to the hospital 4 months after the final denosumab dose with polyuria, polydipsia, fatigue, nausea and abdominal pain. Work-up revealed serum Ca 15.3 mg/dL (N: 8.4–10.2), PTH <3 pg/mL (N: 24–86), 25-OH vitamin D 32 ng/mL (N: >19 ng/mL), 1,25-dihydroxyvitamin D 6.7 pg/mL (N: 19.9–79.3), and urine Ca/Cr 0.48. Renal ultrasound showed normal kidneys with a small amount of layering debris in the bladder. During hospitalization, he received IV fluids, 1 dose of furosemide, 3 doses of calcitonin, 24 hours of hydrocortisone, and a single 0.5 mg/kg dose of pamidronate. He was discharged 48 hours after the bisphosphonate with serum Ca 9.5 mg/dL. He returned with serum Ca 13.5 mg/dL 9 days after the pamidronate and was readmitted. He again received 4 doses of calcitonin and 1 dose of pamidronate (0.5 mg/kg). Calcium levels improved to 9.5 mg/dL at discharge but rose to 11.6 mg/dL a week later. He received a 0.05 mg/kg dose of zoledronate outpatient, with improvement in serum Ca to 10.1 mg/dL. A week later, he twisted his ankle, resulting in transverse impacted buckle fractures of his left distal tibia and fibula; no lytic or sclerotic lesions were noted on x-ray. His leg was immobilized by Orthopedics. Calcium levels remained within range (9.9 mg/dL) 7 months after the zoledronate. Conclusion: Rebound hypercalcemia can occur months after denosumab withdrawal, indicating the need for close monitoring of calcium levels in patients who receive this drug. The hypercalcemia appears to respond best to bisphosphonates, with a more sustained response to zoledrenate compared to pamidronate.

Objective: Neutropenia can occur in untreated autoimmune hyperthyroidism (AIH) or in association with treatment with the anti-thyroid drug, methimazole (MMI). Starting MMI in children and adolescents with AIH and pre-existing neutropenia could thus be worrisome. The aim was to describe the prevalence of neutropenia in pediatric AIH, prior to antithyroid drug therapy and to assess the effect of antithyroid drugs on neutrophil count. Methods: Patients with AIH attending a pediatric endocrinology clinic were retrospectively reviewed. Absolute neutrophil count (ANC) data at presentation and during anti-thyroid treatment for up to 24 weeks was collected. AIH was defined as elevated free thyroxine (fT4) or free tri-iodothyronine (fT3), suppressed thyroid stimulating hormone, and positive thyroid autoantibodies. Neutropenia was defined as ANC <1500 cells/μL. Results: Thirty-one patients (71% female) were included with a median interquartile range (IQR) age of 14.71 (11.89-17.10) years. Neither fT4 nor fT3 levels correlated with ANC at presentation (r s =0.22, p=0.24 and r s =0.13, p=0.54, respectively). 26/31 (84%) had normal baseline ANC. None developed neutropenia with thionamides. 5/31 (16%) had baseline neutropenia (median ANC 1,200/μL; IQR 874-1200). Four of these five started MMI at diagnosis while one was started on propranolol only but MMI was started one week later. All five normalized ANC within 24 weeks. Conclusion: In this cohort, 16% of AIH patients had neutropenia at presentation, but this resolved in the short term and did not worsen with thionamides. Thionamides may be used with caution in these patients with close monitoring of blood counts.