Musculoskeletal complications of Cushing syndrome.

Prolonged exposure to an excess of glucocorticosteroids (GCs), both endogenous and exogenous, leads to a wide range of comorbidities, including cardiovascular, metabolic, psychiatric, and musculoskeletal disorders. The latter comprise osteopenia and osteoporosis leading to skeletal fractures and myopathy. Although endogenous hypercortisolemia is a rare disorder, GCs are among the most frequently prescribed drugs, often administered chronically and despite multiple side effects, impossible to taper off due to therapeutic reasons. The pathophysiology of the effect of GC excess on bone often leads to fractures despite normal or low-normal bone mineral density and it includes direct (mainly disturbance in bone formation processes, through inactivation of the Wnt/ß-catenin signalling pathway) and indirect mechanisms (through suppressing the gonadal and somatotrophic axis, and also through antagonizing vitamin D actions). Glucocorticosteroid-induced fast-twitch, glycolytic muscles atrophy occurs due to increased protein catabolism and impaired synthesis. Protein degradation is a result of activation of the ubiquitin proteasome and the lysosomes stimulated through overexpression of several atrogenes (such as FOXO-1 and atrogin-1). This review will discuss pathophysiology, clinical presentation, prevention, and management of GC-induced osteoporosis (including calcium and vitamin D supplementation, and bisphosphonates) and myopathy associated with GC excess.

Therapeutic plasma exchange with albumin as a valuable method of preparing thyrotoxic patients for a life-saving thyroidectomy.

Hyperthyroidism affects approximately 1.2% of the population and its routine treatment includes antithyroid drugs (ATDs), radioiodine and surgery. Management of patients with resistance or contraindications to ATDs who require thyroidectomy may be challenging. We present the experience of our department in preparing thyrotoxic patients for life-saving thyroidectomy by using therapeutic plasma exchange (TPE) with albumin: one patient with Graves' disease and previous history of agranulocytosis and cholestatic jaundice after ATDs and two patients with amiodarone-induced thyrotoxicosis. Five to six TPEs were applied to each patient resulting in a decrease of fT3 by 57% to 83%, fT4 by 21% to 60% and decrease/normalization of total thyroid hormones. All patients underwent surgery successfully. In case of drug-resistant thyrotoxicosis or contraindications to ATDs, TPE can be a valuable tool in preparing patients for surgery. Albumin used as a replacement fluid appears to be effective in ameliorating clinical and laboratory symptoms of thyrotoxicosis.

Adrenal (131)I-6ß-iodomethylnorcholesterol scintigraphy in choosing the side for adrenalectomy in bilateral adrenal tumors with subclinical hypercortisolemia.

PURPOSE: Adrenal scintigraphy with 131I-6ß-iodomethylnorcholesterol is considered by several authors the gold standard for assessing tumors with subclinical hypercortisolemia. However, most of the described series consist mainly of cases with unilateral lesions. The aim of our study was to assess whether scintigraphy is useful in choosing the adrenalectomy side in the case of bilateral adrenal tumors with subclinical hypercortisolemia. METHODS: The study focused on 15 consecutive patients with benign bilateral adrenal tumors and subclinical hypercortisolemia. The scintigraphy with 131I-6ß-iodomethylnorcholesterol was performed. Fourteen patients underwent unilateral adrenalectomy; the gland with predominant uptake on scintigraphy was removed. Cortisol and ACTH concentrations were measured one and six months after surgery. Post-dexamethasone cortisolemia was assessed six months after surgery. To date, the patients have been under postoperative observation for 1-4 years. RESULTS: Four patients showed unilateral uptake of radiotracer, and nine patients showed predominant accumulation of radiotracer in one of the adrenal glands. The smaller tumor was predominant in 2 cases. Percentage of activity on the predominant side correlates positively with the difference between tumors' diameters. Unilateral uptake of radiotracer predicts long-lasting postoperative insufficiency of the second adrenal gland. Excision of predominating tumor led to cessation of hypercortisolemia in all patients. CONCLUSIONS: The corticoadrenal scintigraphy is useful in choosing the side for operation in the case of bilateral adrenal tumors with subclinical hypercortisolemia.

Measurement of salivary thyroid hormones using the LC-MS/MS technique in a clinical setting.

Background: Saliva could be an attractive alternative to blood for assessing thyroid hormonal function. Objectives: Our goal was to determine if the levels of thyroid hormones in saliva can accurately reflect a person's thyroid status and if they consistently correlate with the levels of the same hormones in the blood. Design: We conducted a cross-sectional study. Methods: We enrolled a total of 109 participants with different thyroid conditions. We measured TSH (Thyroid-Stimulating Hormone), free T3 (fT3), and free T4 (fT4) in the blood using two different immunoassay methods: electrochemiluminescence immunoassay (ECLIA) and chemiluminescence immunoassay (CLIA). Saliva samples were collected using Salivette® tubes, and then we analyzed the levels of thyroid hormones in the saliva using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Results: Comparing salivary and serum levels of thyroid hormones, we observed significantly lower fT4 and higher fT3 levels in saliva (p < 0.001), regardless of the measurement method. We also found that salivary fT3 and fT4 levels were positively correlated in the entire group of participants (p < 0.001, R 0.575), as well as in those with TSH values within the normal reference range (p < 0.001, R 0.570). We further divided participants based on their TSH reference intervals and assessed the correlations between serum and salivary thyroid hormones within these groups. We also discovered that taking exogenous levothyroxine influenced the correlations between serum and salivary thyroid hormones. Thyroid antibodies did not have a significant impact on the levels of thyroid hormones in both serum and saliva. Conclusion: This study demonstrates that salivary thyroid hormones can partially reflect the levels of these hormones in the blood. Saliva may be a useful tool in a clinical setting for patients with thyroid antibodies, but it may not be as effective for those who are taking levothyroxine as a treatment.

Persistent hypercalcaemia associated with two pathogenic variants in the CYP24A1 gene and a parathyroid adenoma-a case report and review.

Introduction: 24-Hydroxylase, encoded by the CYP24A1 gene, is a crucial enzyme involved in the catabolism of vitamin D. Loss-of-function mutations in CYP24A1 result in PTH-independent hypercalcaemia with high levels of 1,25(OH)2D3. The variety of clinical manifestations depends on age, and underlying genetic predisposition mutations can lead to fatal infantile hypercalcaemia among neonates, whereas adult symptoms are usually mild. Aim of the study: We report a rare case of an adult with primary hyperparathyroidism and loss-of-function mutations in the CYP24A1 gene and a review of similar cases. Case presentation: We report the case of a 58-year-old woman diagnosed initially with primary hyperparathyroidism. Preoperatively, the suspected mass adjoining the upper pole of the left lobe of the thyroid gland was found via ultrasonography and confirmed by 99mTc scintigraphy and biopsy as the parathyroid gland. The patient underwent parathyroidectomy (a histopathology report revealed parathyroid adenoma), which led to normocalcaemia. After 10 months, vitamin D supplementation was introduced due to deficiency, and the calcium level remained within the reference range. Two years later, biochemical tests showed recurrence of hypercalcaemia with suppressed parathyroid hormone levels and elevated 1,25(OH)2D3 concentrations. Further investigation excluded the most common causes of PTH-independent hypercalcaemia, such as granulomatous disease, malignancy, and vitamin D intoxication. Subsequently, vitamin D metabolites were measured using LC-MS/MS, which revealed high levels of 25(OH)D3, low levels of 24,25(OH)2D3 and elevated 25(OH)2D3/24,25(OH)2D3 ratios, suggesting a defect in vitamin D catabolism. Molecular analysis of the CYP24A1 gene using the NGS technique revealed two pathogenic variants: p.(Arg396Trp) and p.(Glu143del) (rs114368325 and rs777676129, respectively). Conclusions: The diagnostic process for hypercalcaemia becomes complicated when multiple causes of hypercalcaemia coexist. The measurement of vitamin D metabolites using LC-MS/MS may help to identify carriers of CYP24A1 mutations. Subsequent molecular testing may contribute to establishing the exact frequency of pathogenic variants of the CYP24A1 gene and introducing personalized treatment.

Pheochromocytoma/paraganglioma-associated cardiomyopathy.

Pheochromocytoma/paraganglioma (PPGL) are neuroendocrine tumors that frequently produce and release catecholamines. Catecholamine excess can manifest in several cardiovascular syndromes, including cardiomyopathy. PPGL-induced cardiomyopathies occur in up to 11% of cases and are most often associated with an adrenal pheochromocytoma (90%) and rarely with a paraganglioma derived from the sympathetic ganglia (10%). PPGL-associated cardiomyopathies can be chronic or acute, with takotsubo cardiomyopathy being the most often reported. These two types of PPGL-induced cardiomyopathy seem to have different pathophysiological backgrounds. Acute catecholaminergic stress inundates myocardial ß-adrenoceptors and leads to left ventricle stunning and slight histological apoptosis. In chronic cardiomyopathy, prolonged catecholamine exposure leads to extended myocardial fibrosis, inflammation, and necrosis, and ultimately it causes dilated cardiomyopathy with a low ejection fraction. Sometimes, especially in cases associated with hypertension, hypertrophic cardiomyopathy can develop. The prognosis appears to be worse in chronic cases with a higher hospital mortality rate, higher cardiogenic shock rate at initial presentation, and lower left ventricular recovery rate after surgery. Therefore, establishing the correct diagnosis at an early stage of a PPGL is essential. This mini-review summarizes current data on pathophysiological pathways of cardiac damage caused by catecholamines, the clinical presentation of PPGL-induced cardiomyopathies, and discusses treatment options.

Macro-GH - A clinical entity causing a diagnostic challenge - A case report.

AIM: Presentation of a new case of a patient with macro-GH, that may interfere with different GH assays leading to false-positive results in serum samples. CASE PRESENTATION: A 61-year-old female was referred with a pituitary macroadenoma and elevated growth hormone levels. The laboratory tests showed increased fasting GH level, measured by a sandwich chemiluminescence immunoassay (LIAISON® XL) without suppression on oral glucose tolerance test and normal IGF-1. The patient did not have the typical signs and symptoms of acromegaly. The patient underwent a transsphenoidal resection of a pituitary tumor, showing only α-subunit immunostaining. Postoperative GH levels remained elevated. An interference in the determination of GH level was suspected. GH was analyzed by three different immunoassays, UniCel DxI 600, Cobas e411 and hGH-IRMA. Heterophilic antibodies and rheumatoid factor were not detected in serum sample. GH recovery after precipitation with 25 % polyethylene glycol (PEG) was 12 %. Size-exclusion chromatography confirmed the presence of macro-GH in serum sample. CONCLUSION: If results of laboratory tests are not consistent with the clinical findings, the presence of an interference within immunochemical assays could be suspected. To identify interference caused by the macro-GH, the PEG method and size-exclusion chromatography should be used.

Poor Performance of Angiotensin II Enzyme-Linked Immuno-Sorbent Assays in Mostly Hypertensive Cohort Routinely Screened for Primary Aldosteronism.

Primary aldosteronism (PA) is the most common, but broadly underdiagnosed, form of hormonal hypertension. To improve screening procedures, current biochemical approaches aim to determine newly appreciated angiotensin II (Ang II) and calculate the aldosterone-to-angiotensin II ratio (AA2R). Thus, the aim of this study was to assess the diagnostic performance of these screening tests in comparison to the aldosterone-to-direct renin ratio (ADRR), which is routinely used. Cheap and available ELISA was used for Ang II measurement. To our knowledge, this is the first study of this laboratory method's usage in PA. The study cohort included 20 PA patients and 80 controls. Ang II concentrations were comparable between PA and non-PA patients (773.5 vs. 873.2 pg/mL, p = 0.23, respectively). The AA2R was statistically significantly higher in PA group when compared with non-PA (0.024 vs. 0.012 ng/dL/pg/mL, p < 0.001). However, the diagnostic performance of the AA2R was significantly worse than that of the ADRR (AUROC 0.754 vs. 0.939, p < 0.01). The sensitivity and specificity of the AA2R were 70% and 76.2%, respectively. Thus, the AA2R was not effective as a screening tool for PA. Our data provide important arguments in the discussion on the unsatisfactory accuracy of renin−angiotensin system evaluation by recently repeatedly used ELISA tests.

Thyroid autoimmunity and its negative impact on female fertility and maternal pregnancy outcomes.

Thyroid autoimmunity (TAI) is commonly defined as the presence of thyroperoxidase antibodies (TPOAbs) and/or thyroglobulin antibodies (TgAbs), which predisposes an individual to hypothyroidism. TAI affects nearly 10% of women of reproductive age and evokes great interest from clinicians because of its potentially negative impact on female fertility and pregnancy course. In this mini-review, we review the current literature concerning the influence of TPOAb or TPOAb/TgAb positivity without thyroid dysfunction on reproduction. TAI may negatively affect female fertility; several studies have found an increased prevalence of TAI in infertile women, especially in those with unexplained infertility and polycystic ovary syndrome. According to some observations, TAI might also be connected with premature ovarian insufficiency and endometriosis. The relationship between TAI and an increased risk of pregnancy loss is well documented. The pathophysiological background of these observations remains unclear, and researchers hypothesize on the direct infiltration of reproductive organs by thyroid antibodies, co-existence of TAI with other autoimmune diseases (either organ specific or systemic), immunological dysfunction leading to inhibition of immune tolerance, and relative thyroid hormone deficiency. Interestingly, in the current literature, better outcomes of assisted reproductive technology in women with TAI have been reported compared with those reported in earlier publications. One plausible explanation is the more widespread use of the intracytoplasmic sperm injection method. The results of randomized clinical trials have shown that levothyroxine supplementation is ineffective in preventing adverse pregnancy outcomes in women with TAI, and future research should probably be directed toward immunotherapy.

ProSAAS peptide of the granin protein family in biochemical diagnostics of pheochromocytoma.

INTRODUCTION: Pheochromocytoma is a hormonally active tumour originating from neuroendocrine cells of the adrenal medulla. Chromogranin A (CgA) and peptide proSAAS belong to the family of granins and are present in neuroendocrine cells of adrenal medulla, from where they are released to circulation, along with catecholamines. The aim of this study was to assess the usability of proSAAS peptide assay in patients with adrenal pheochromocytoma. MATERIAL AND METHODS: 23 patients (13 females and 10 males) with adrenal pheochromocytoma (benign in 18 patients and malignant in 5) confirmed by histopathology examination, and 35 blood donors as a control group. Plasma free metanephrines, CgA, and proSAAS peptide levels were measured in all participants. RESULTS: CgA and proSAAS levels in the group of pheochromocytoma patients vs. the control were: 209 ng/mL and 0.8 ng/mL vs. 59 ng/mL and 0.3 ng/mL (p < 0.001), respectively. The following sensitivity and specificity indexes were obtained from ROC curves for CgA: 83% and 92%, respectively, and for the proSAAS peptide: 39% and 88%, respectively. The combination of 2 parameters: normetanephrine and proSAAS (96% and 100%) had a high diagnostic value, and the value of all determined parameters together (metanephrine, normetanephrine, CgA, and proSAAS) was 100%. CONCLUSION: A single determination of the proSAAS peptide level is associated with a rather low diagnostic value. But collective determination of CgA and proSAAS may be an additional, valuable tool in biochemical diagnostics of pheochromocytoma.

FGF21 Is Released During Increased Lipogenesis State Following Rapid-Onset Radioiodine-Induced Hypothyroidism.

Background: FGF21 pharmacological treatment reverses fatty liver and lowers serum triglyceride concentration but FGF21 serum level is increased in hepatic steatosis. FGF21 secretion is induced by thyroid hormones in vitro. Purpose: To determine the influence of thyroid hormones and metabolic changes secondary to thyroid dysfunction on FGF21 secretion in humans. Materials and Methods: This was a case-control study. 82 hyperthyroid and 15 hypothyroid patients were recruited together with 25 healthy controls. Of those with hyperthyroidism, 56 received radioiodine treatment and 42 of them achieved hypothyroidism and then euthyroidism within one year following therapy. Radioiodine-induced hypothyroidism developed abruptly within a six week interval between clinic visits. FGF21 serum levels were determined with an ELISA method. Results: Serum FGF21 levels did not differ in hyper- and hypothyroid patients in comparison to controls [median 103.25 (interquartile range, 60.90-189.48) and 86.10 (54.05-251.02) vs 85.20 (58.00-116.80) pg/mL P=0.200 and 0.503, respectively]. In hyperthyroid patients treated with radioiodine, serum FGF21 levels increased significantly in rapid-onset hypothyroidism in comparison to the hyperthyroid and euthyroid phase [median 160.55 (interquartile range, 92.48 - 259.35) vs 119.55 (67.78-192.32) and 104.43 (55.93-231.93) pg/mL, P=0.034 and 0.033, respectively]. The rising serum FGF21 level correlated positively with serum triglycerides (Spearman coefficient rs=0.36, P=0.017) and inversely with serum SHBG (rs=-0.41, P=0.007), but did not correlate with thyroid hormone levels. Conclusions: There was a transient increase in FGF21 serum level during rapid-onset hypothyroidism following radioiodine treatment. There was no association between FGF21 serum level and thyroid hormones. In radioiodine-induced hypothyroidism, the rising serum FGF21 concentration correlated positively with rising serum triglycerides and negatively with falling SHBG, reflecting increased hepatic lipogenesis.

The Effect of a Single High Dose of Vitamin D on Serum Levels of Its Metabolites in the Elderly.

BACKGROUND: Vitamin D is a dietary micronutrient responsible for calcium and phosphorus metabolism and multiple extraskeletal actions. The assessment of vitamin D status is commonly based on measurement of 25(OH)D total concentration in serum. However, the usage of liquid chromatography with tandem mass spectrometry (LC-MS/MS) technique allows to reliably assess a panel of vitamin D metabolites in serum or plasma, which may help to investigate the metabolic paths of vitamin D, especially in populations at risk of deficiency. METHODS: A randomized, two-arms, open study was conducted on 58 patients (28 female and 30 male; aged from 61 to 96 years old). The primary aim was to assess the effects of a single, high, oral dose of vitamin D3 (120,000 IU) on serum 25(OH)D3, 25(OH)D2, 24,25(OH)2D3, 3-epi-25(OH)D3, 1,25(OH)2D3, 24,25(OH)2D3/25(OH)D3 ratio, and 25(OH)D3/3-epi-25(OH)D3 ratio concentration (measured by LC-MS/MS) at baseline, 3 days and 7 days after administration, compared to control group. The secondary aim was assessment of influence of percentage of fat tissue on serum metabolites of vitamin D and their changes after bolus dose. RESULTS: 56.6% study group attained a serum 25(OH)D3 concentration >30 ng/mL. All subjects, except for one patient achieved a serum 25(OH)D3 concentration >20 ng/mL after administration. No one exceed reference value of vitamin D (30-50 ng/mL). Among participants who received vitamin D3 there were significant increase in 25(OH)D3, 3-epi-25(OH)D3, 1,25(OH)2D3, 24,25(OH)2D3 on 3rd day after administration. 24,25(OH)2D3 concentration gradually grew, achieving the highest concentration on 7th day. The percentage increase of 25(OH)D3 was negatively correlated with baseline 25(OH)D3 (r = -0.688, p = 0.001). Positive correlation between percentage increase in 25(OH)D3 and a percentage increase serum concentration of 24,25(OH)2D3 (r = 0.954, p < 0.001), 3-epi-25(OH)D3 (r = 8.03, p < 0.001) and 1,25(OH)2D3 (r = 0.789, p <0.001) were found. None of the study participants developed hypercalcemia. The baseline concentration of analyzed metabolites of vitamin D in serum and their percentage increase were neither dependent on BMI nor percentage of fat tissue. CONCLUSIONS: High dose of vitamin D rapidly increases 25(OH)D3 concentration in the elderly patients. The response to the bolus of vitamin D includes activation of 3-epimerase, followed by production of 24,25(OH)2D3, which protects from excessive increase of active form of vitamin D.

Evaluation of plasma ACTH in the metyrapone test is insufficient for the diagnosis of secondary adrenal insufficiency.

Objective: To determine whether a single measurement of ACTH instead of less available in daily practice 11-deoxycortisol assay is sufficient to rule out or confirm secondary adrenal insufficiency (SAI) in the short Metyrapone test. Design: A retrospective analysis of diagnostic tests (Metyrapone and Synacthen tests) performed at our Center between 2016 and 2018 in patients with suspicion of secondary adrenal insufficiency. Material and methods: In 103 patients short metyrapone test was performed with assessment of 11-deoxycortisol and ACTH concentration after Metyrapone administered at midnight. In 89 of them short Synacthen (SST) test was also done (1 or/and 250 mcg 1-24ACTH). ROC curves have been performed to evaluate the diagnostic performance of ACTH level in metyrapone test as the predictor of secondary adrenal insufficiency (SAI) analysing sensitivity and specificity for various possible thresholds proposed in literature. Results: 40 (39%) of examined subjects were diagnosed as SAI, basing on post-Metyrapone 11-deoxycortisol concentration below 70 µg/l. In this group ACTH concentration was 128.1 ng/l (95% CI 96.8-159.4) versus 289.9 ng/l (95% CI 249.1-330.9) in patients with proper adrenal response. There was only a moderate positive correlation between ACTH and 11-deoxycortisol concentrations (r=0.5; p<0.05). The best cut off value of ACTH in relation to 11-deoxycortisol serum concentrations was 147 ng/l - with sensitivity of 73.2% and specificity 83.9%. However, plasma ACTH was>200ng/ml (the highest threshold proposed in literature) in 8 cases (20%) with positive diagnosis of SAI made on the basis of low 11-deoxycortisole and confirmed in short Synacthen test. Conclusion: Our results indicate that for a valuable evaluation of the results of the metyrapone test, the more readily available plasma ACTH assay cannot replace the measurement of 11-deoxycortisol concentrations.

Subclinical hypothyroidism in pregnancy: controversies on diagnosis and treatment.

The negative impact of even subtle maternal thyroid hormone deficiency on the pregnancy outcome and intellectual development of the progeny has been known for many years, but unfortunately the diagnosis and treatment of subclinical hypothyroidism in pregnant women still evokes controversies. Due to physiological changes in thyroid function and thyroid hormones metabolism during pregnancy, the trimester­specific reference ranges for thyroid­stimulating hormone (TSH) and free thyroid hormones should be established. However, because of interassay variability and other confounders including ethnicity and iodine intake, such norms are reliable only for local populations and a specific laboratory method. In turn, the fixed reference ranges suggested by endocrine societies may carry a risk of misclassificating some healthy pregnant women to be hypothyroid. The effect of levothyroxine treatment on pregnancy and children's cognitive outcomes remains unclear. Therapeutic benefits in decreasing miscarriage and preterm delivery rates were observed when intervention was held in the first trimester in women with a TSH level between 2.5 to 10 mU/l, mainly higher than or equal to 4 mU/l. The possible harmful effect of treatment includes preterm delivery, gestational diabetes, hypertension, and pre­eclampsia. The only 3 prospective, randomized, placebo­controlled trials evaluating the efficacy of levothyroxine therapy on children's intelligence quotient were started in the second trimester, which may be too late to demonstrate differences between treatment and placebo groups. Awaiting the results of future trials, clinicians should be aware of the fact that low­dose levothyroxine at a daily dose of 25 to 50 µg is probably not harmful and may be beneficial, but the routine implementation of the therapy in each pregnant women with a TSH level exceeding 2.5 mU/l seems too premature.

Improvements in Quality of Life and Thyroid Parameters in Hypothyroid Patients on Ethanol-Free Formula of Liquid Levothyroxine Therapy in Comparison to Tablet LT4 Form: An Observational Study.

Levothyroxine (LT4) is a standard therapy in hypothyroidism; however, its bioavailability and therapeutic effects might be affected by many factors. Data shows that therapy with liquid LT4 characterized by quicker pharmacokinetics provides better thyroid hormones control than tablet LT4. We addressed the quality of life (QoL) and efficacy of the new ethanol-free formula of liquid LT4 (Tirosint®SOL) treatment in 76 euthyroid patients with primary (PH, n = 46) and central hypothyroidism (CH, n = 30), and compared the results to retrospective data on equivalent doses of tablet L-T4 therapy. After 8 weeks of liquid LT4 therapy, we found a significant improvement in QoL in both PH and CH patients. TSH levels were unaltered in PH patients. Free hormone levels (fT4 and fT3) increased in all the patients, with the exception of fT3 in the CH group. SHBG and low-density lipoprotein (LDL) also improved. Liquid LT4 therapy provided a better thyroid hormone profile and improvement in patients' QoL than the tablet form, which was possibly due to the more favorable pharmacokinetics profile resulting in better absorption, as suggested by the increased free thyroid hormone levels. In summary, this is the first study addressing the QoL in hypothyroid patients, including primary and central hypothyroidism, treated with liquid LT4 formula in everyday practice.

Chromogranin A (CgA)--the influence of various factors in vivo and in vitro, and existing disorders on it's concentration in blood.

Chromogranin A (CgA) is regarded as a major, nonspecific neuroendocrine tumour (NET) marker. The results of CgA blood concentration, however, may actually be influenced by various factors or coexisting pathological conditions. Among the factors causing a substantial increase of the blood CgA concentration are: treatment with proton-pump inhibitors or H2-receptor blockers, chronic atrophic gastritis (type A), impaired renal function, prostate cancer and BPH, and rheumatoid arthritis with high level of RF IgM. In addition, the sort of investigated biological material (whether it is serum or plasma) is of importance. There are also many conditions which may have a moderate or little influence on the concentration of CgA, among them are: inflammatory bowel disease (ulcerative colitis and Crohn's disease), deteriorating liver function, untreated essential hypertension, heart failure, hypercortisolism, pregnancy, and, in some subjects, ingestion of a meal. Proper assessment of the CgA results requires detailed knowledge about various factors, drugs, and pathological conditions influencing its concentration in blood.

The differences in chromogranin A (CgA) concentrations measured in serum and in plasma by IRMA and ELISA methods.

INTRODUCTION: Chromogranin A (CgA) is regarded as a major, nonspecific marker of neuroendocrine tumors (NET). Its estimation appears helpful for diagnostic purposes and is particularly useful for monitoring the treatment of NET. It must be kept in mind, however, that various factors, drugs, or coexisting diseases may influence the outcome of CgA measurement in blood. One such analytical factor is the sort of studied biological material, whether it is plasma or serum. The aim of our study was to compare directly the results of CgA concentrations measured in serum and in plasma by IRMA and ELISA. MATERIAL AND METHODS: We analysed 122 samples of EDTA-plasma and 122 samples of serum by IRMA method, 20 samples of EDTAplasma and 20 samples of serum by IRMA and ELISA, 25 heparinised-plasma samples and 25 samples of EDTA-plasma by IRMA and ELISA methods, and 8 EDTA-plasma, heparinised-plasma, and serum samples by IRMA and ELISA. The material for comparative study was obtained during the same blood collection from the same subjects (volunteers and patients with NET). CgA was measured with the use of kits manufactured by CIS bio International (France). RESULTS: CgA concentrations were markedly higher in plasma than in serum. Using the IRMA method, the difference in the CgA range between 10-100 ng/mL approached 20-70% (median 61 v. 42), in the range 101-300 ng/mL--12-60% (median 147 v. 101), and in the CgA range 301-1076 ng/mL--14-40% (median 486 v. 356). The differences between results in serum and plasma using ELISA were similar but slightly smaller. There was no significant difference between CgA levels in EDTA and heparinised-plasma samples, and the results of measurements performed by IRMA and ELISA in most cases were similar. CONCLUSIONS: Referring each individual CgA result to the proposed reference range (or cut-off value) we must take into account whether the measurement is performed in plasma or in serum.

[Chromogranin A (CgA) - characteristic of the currently available laboratory methods and conditions which can influence the results]. / Chromogranina A (CgA)- charakterystyka dostepnych metod badawczych i unwarunkowan mogacych miec wplyw na uzyskane wyniki.

Chromogranin A is a main, nonspecific neuroendocrine tumor marker (NET). It's estimation was applied for diagnostic purposes and for monitoring the treatment of NET. Currently few commercial assays are available allowing measurement of CgA concentration in serum or plasma. These methods have various sensitivity and specificity and differ in many analitycal parameters. Numerous factors and pathologies may influence the outcome of the CgA measurement. Therefore, a review article on this matter may be useful for clinical and laboratory practice.

The effect of biotin interference on the results of blood hormone assays.

Approximately 70% of medical decisions are made based on results of laboratory investigations. Immunochemical methods are used most commonly in routine laboratory diagnostics of endocrine disorders. Those methods are limited by susceptibility of the immunochemical reaction to various interferences. Interference may be caused by the presence of autologous antibodies, heterophilic antibodies, or paraproteins in the blood serum, by cross-reactions with similar reagents, haemolysis, significant lipidaemia, or hyperbilirubinaemia. Some recent reports have indicated a significant effect of biotin on the reliability of laboratory investigations. Biotin is a water-soluble vitamin belonging to the B group. It is present in popular dietary supplements - alone or as a component of multi-vitamin formulas - and it is advertised as a remedy to falling out and fragility of hair and nails. Due to its low molecular weight and a strong affinity to streptavidin, biotin is used in many immunochemical tests. Due to a strong and stable bond of streptavidin and biotin, analytical methods using the streptavidin (avidin)-biotin system are characterised by superior sensitivity, and they allow determination of very low levels of the tested substance in biological material. The presence of exogenous biotin in a sample may cause interference when using tests that utilise the streptavidin (avidin)-biotin system. Interference of biotin with immunochemical tests depends on several factors: the construction of the immunochemical test, the dose used by the patient, the biotin concentration in the sample, and most of all - the time from the last dose to the collection of biological material for laboratory testing. In this paper we present some practical recommendations and a procedure to be followed in the case of suspected interference of biotin in immunochemical assays, for clinicians and laboratory diagnosticians.