Tumor-induced osteomalacia: experience from a South American academic center

The majority of tumor-induced osteomalacia cases have been reported in the Northern Hemisphere and Asia. In this first series of South American patients, we show that the clinical presentation and sensitivity of plasmatic fibroblast growth factor 23 and somatostatin analog-based imaging are similar to those described in other populations.

INTRODUCTION

Describe the experience of clinical presentation, diagnostic study, and treatment of patients with tumor-induced osteomalacia (TIO) in a South American academic center in comparison to literature.

METHODS

Analysis of the records of patients diagnosed with TIO. The clinical presentation, diagnostic studies, and treatment were analyzed. Fibroblast growth factor 23 (FGF23) was measured by ELISA.

RESULTS

Six patients were diagnosed with TIO during the studied period. The patients' median age was 53 years (range 22-64). All patients presented with weakness and pain in the extremities. Four experienced fractures during their evolution. The median time to diagnosis was 4.5 years (1-20). Biochemical studies showed hypophosphatemia, median of 1.4 mg/dL (1.2-1.6), with low maximum rates of tubular reabsorption of phosphate adjusted for glomerular filtration rate. FGF23 was elevated in 4/6 patients and inappropriately normal in the other two. In three patients, the location of the tumor was clinically evident and confirmed with anatomical imaging. In the remaining patients, two tumors were located with ⁶⁸Ga DOTATATE-PET/CT and one with OctreoScan. The causal tumors were located in the lower extremities in five patients and invading the frontal sinus in one patient. In all patients, tumors were successfully removed. Within 14 days, there was normalization of phosphate and FGF23 levels and resolution of clinical symptoms in all patients. In all cases, the histopathology was compatible with a phosphaturic mesenchymal tumor.

CONCLUSIONS

The clinical presentation, delay time to diagnosis, FGF23 diagnostic sensitivity and histopathology in this first series of South American patients is similar to those described in other populations. The success of localization by somatostatin analog-based imaging, suggests this may the optimal imaging modality.

High sodium intake is associated with increased glucocorticoid production, insulin resistance and metabolic syndrome

OBJECTIVE

High sodium (HS) diet is associated with hypertension (HT) and insulin resistance (IR). We evaluated whether HS diet was associated with a dysregulation of cortisol production and metabolic syndrome (MetS).

PATIENTS AND MEASUREMENTS

We recruited 370 adults (18-85 years, BMI 29·3 ± 4·4 kg/m(2) , 70% women, 72% HT, 61% MetS). HS diet (urinary sodium >150 mEq/day) was observed in 70% of subjects. We measured plasma hormones, lipid profile, urinary free cortisol (UFC) and cortisol tetrahydrometabolites (THM).

RESULTS

Urinary sodium was correlated with UFC (r = +0·45, P < 0·001), cortisol THM (r = +0·41, P < 0·001) and inversely with adiponectin, HDL and aldosterone, after adjusting by age, gender and BMI. Subjects with high, compared with adequate sodium intake (50-149 mEq/day) had higher UFC (P < 0·001), THM (P < 0·001), HOMA-IR (P = 0·04), HT (81% vs 50%, P < 0·001), MetS (69% vs 41%, P < 0·001) and lower adiponectin (P = 0·003). A multivariate predictive model adjusted by confounders showed a high discriminative capacity for MetS (ROC curve 0·878) using four clinical variables: HS intake [OR = 5·6 (CI 2·3-15·3)], HOMA-IR [OR 1·7 (1·3-2·2)] cortisol THM [OR 1·2 (1·1-1·4)] and adiponectin [OR = 0·9 (0·8-0·9)], the latter had a protective effect.

CONCLUSIONS

High sodium diet was associated with increased urinary cortisol and its metabolites. Also, HS diet was associated with HT, insulin resistance, dyslipidaemia and hypoadiponectinaemia, even when adjusting by confounding variables. Further, we observed that high salt intake, IR and higher cortisol metabolites, alone or combined in a clinical simple model, accurately predicted MetS status, suggesting an additive mechanism in obesity-related metabolic disorders.

Long-term dietary sodium restriction increases adiponectin expression and ameliorates the proinflammatory adipokine profile in obesity

BACKGROUND/AIM

Obesity is associated with changes in adiponectin and pro-inflammatory adipokines. Sodium intake can affect adipokine secretion suggesting a role in cardiovascular dysfunction. We tested if long-term dietary sodium restriction modifies the expression of adiponectin and ameliorates the pro-inflammatory profile of obese, diabetic mice.

METHODS/RESULTS

Db/db mice were randomized to high sodium (HS 1.6% Na+, n = 6) or low sodium (LS 0.03% Na+, n = 8) diet for 16 weeks and compared with lean, db/+ mice on HS diet (n = 8). Insulin levels were 50% lower in the db/db mice on LS diet when compared with HS db/db (p < 0.05). LS diet increased cardiac adiponectin mRNA levels in db/db mice by 5-fold when compared with db/db mice on HS diet and by 2-fold when compared with HS lean mice (both p < 0.01). LS diet increased adiponectin in adipose tissue compared with db/db mice on HS diet, achieving levels similar to those of lean mice. MCP-1, IL-6 and TNF-α expression were reduced more than 50% in adipose tissue of db/db mice on LS diet when compared with HS db/db mice (all p < 0.05), to levels observed in the HS lean mice. Further, LS db/db mice had significantly reduced circulating MCP-1 and IL-6 levels when compared with HS db/db mice (both p < 0.01).

CONCLUSION

In obese-diabetic mice, long-term LS diet increases adiponectin in heart and adipose tissue and reduces pro-inflammatory factors in adipose tissue and plasma. These additive mechanisms may contribute to the potential cardioprotective benefits of LS diet in obesity-related metabolic disorders.

11β-hydroxysteroid dehydrogenase type 2 polymorphisms and activity in a Chilean essential hypertensive and normotensive cohort

BACKGROUND

11β-hydroxysteroid dehydrogenase type 2 enzyme (11β-HSD2) inactivates cortisol (F) to cortisone (E); its impairment is associated with hypertension. We reported that 15.7% of the Chilean essential hypertensives possessed a high F/E ratio suggesting a partial deficit in 11β-HSD2 activity. It has been reported that the G534A(Glu178/Glu) polymorphism in the HSD11B2 gene is associated with hypertension. Investigate the frequency of the G534A polymorphism and its correlation with the glucocorticoid profile in Chilean essential hypertensive and normotensive subjects.

METHODS

Essential hypertensive outpatients (n = 232) and normotensive subjects (n = 74) were recruited. A change in the AluI restriction enzyme digest pattern, caused by the presence of the G534A polymorphism, was utilized to screen DNA isolated from leukocytes within the cohort before confirmation by sequencing. Plasma renin activity (PRA), serum aldosterone, F, and E were measured by radioimmunoassay. Urinary tetrahydrocortisol (THF), 5α-tetrahydrocortisol (5α-THF), and tetrahydrocortisone (THE) were measured by gas chromatography-mass spectrometry.

RESULTS

G534A polymorphism frequency was similar between hypertensive patients (19 of 232; 8.2%) and normotensive subjects (7 of 74; 9.5%). When categorized by presence or absence of the G534A polymorphism, no significant differences in the serum F/E ratio or other measured biochemical variables were detected. Despite a previous report that the G534A polymorphism is associated with a neighboring C468A (Thr156/Thr) polymorphism, analysis within our cohort showed that only one patient in each group presented with this double polymorphism.

CONCLUSIONS

We report the frequency of the G534A polymorphism in the Spanish-Amerindian population. No correlation was detected between this polymorphism and the presence of hypertension and biochemical parameters in this Chilean cohort.