Search Results

You are looking at 1 - 7 of 7 items for

  • Author: Robin P F Dullaart x
Clear All Modify Search
Restricted access

Thera P Links, Jan F Monkelbaan, Robin PF Dullaart and Timon W van Haeften

A patient with acromegaly and hyperthyroidism due to a growth hormone-, thyrotrophin- and alpha-subunit-secreting pituitary adenoma is described. His deceased father had suffered from a pituitary tumour, and was likely to have had acromegaly as well. Plasma growth hormone and insulin-like growth factor I concentrations were elevated, with levels between 10 and 20 μg/l and 4.4 and 7.3 kU/l, respectively. In spite of hyperthyroidism (free thyroxine, 45 pmol/l; free triiodothyronine, 24 pmol/l), plasma thyrotrophin remained at 2.8 mU/l without any response to thyrotrophin-releasing hormone and could not be suppressed with exogenous administration of triiodothyronine. Plasma alpha-subunits were raised to 3.3–3.7 U/l (normal 0.4–1.1 U/l). Pathological examination of the surgically removed tumour showed a pituitary adenoma with the immunohistochemical presence of growth hormone, thyrotrophin, prolactin and alpha-subunit. This is the first report of a growth hormone-, thyrotrophin- and alpha-subunit-producing pituitary adenoma, which occurred in a familial setting.

Free access

Robin P F Dullaart, Rindert de Vries, Arie van Tol and Wim J Sluiter

Objective: We tested the extent to which altered plasma adipokine levels may contribute to the increased carotid artery intima-media thickness (IMT) associated with type 2 diabetes mellitus and with male gender, independently of conventional cardiovascular risk factors, insulin resistance, and plasma C-reactive protein (CRP).

Design: IMT (mean of three segments of both carotid arteries by ultrasonography), insulin resistance (homeostasis model assessment; HOMAir), plasma CRP, lipids, adiponectin, leptin, resistin, and tumor necrosis factor-α (TNF-α) were measured in 84 type 2 diabetic patients and 85 control subjects.

Results: In diabetic patients, IMT (P<0.001), mean arterial pressure (P<0.001), HOMAir (P<0.001), plasma CRP (P=0.003), triglycerides (P=0.037), leptin (P=0.023), resistin (P=0.003), and TNF-α (P=0.003) levels were higher, whereas high-density lipoproteins (HDL) cholesterol (P<0.001) and adiponectin (P<0.001) levels were lower compared with control subjects. Plasma adiponectin (P<0.001) and leptin (P<0.001) were substantially lower in men than in women. IMT was positively and independently associated with age (P<0.001), diabetes (P=0.049), and male gender (P=0.002) in a multivariate regression model, not including other variables. Further analyses showed that IMT was positively related to age (P<0.001) and plasma triglycerides (P=0.038) and negatively to adiponectin (P<0.001), without independent effects of diabetes, gender, and HOMAir.

Conclusions: Increased IMT in type 2 diabetes may in part be explained by lower plasma adiponectin and higher triglycerides, but not by leptin, resistin, and TNF-α. The gender effect on IMT is related to lower plasma adiponectin.

Free access

Stan Benjamens, Robin P F Dullaart, Wim J Sluiter, Michiel Rienstra, Isabelle C van Gelder and Thera P Links

Objective

Amiodarone is used for the maintenance of sinus rhythm in patients with arrhythmias, but thyroid dysfunction (amiodarone-induced thyrotoxicosis (AIT) or amiodarone-induced hypothyroidism (AIH)) is a common adverse effect. As the onset of AIT and AIH may be unpredictable, the value of long-term regular monitoring of amiodarone treated patients for thyroid dysfunction is still uncertain.

Design

We retrospectively documented the frequency at which overt thyroid dysfunction was preceded by subclinical thyroid dysfunction.

Methods

We included 303 patients treated with amiodarone between 1984 and 2007. AIT was defined as a lowered TSH level with an elevated free thyroxine (FT4) and AIH was defined as an elevated TSH level with a decreased or subnormal FT4. Subclinical AIT was defined as a lowered TSH level with a normal FT4 and subclinical AIH as an elevated TSH level with a normal FT4.

Results

200 men and 103 women, aged 62 ± 12.0 years, suffering from atrial (260) or ventricular (43) arrhythmias, were evaluated. During a median follow-up of 2.8 (1.0–25) years, 44 patients developed AIT and 33 AIH. In 42 (55%) patients who developed AIT/AIH, earlier thyroid function tests showed no subclinical AIT or subclinical AIH. In 35 (45%) patients, AIT/AIH was preceded by subclinical AIT or subclinical AIH (16/44 for AIT and 19/33 for AIH).

Conclusions

In a considerable proportion of patients who developed AIT/AIH, earlier thyroid function tests showed no subclinical AIT/AIH. Less than half of the patients with a subclinical event subsequently developed overt AIT/AIH. This study provides data to reconsider the yield of regular testing of thyroid function to predict overt thyroid dysfunction in amiodarone treated patients.

Free access

Robin P F Dullaart, Albert K Groen, Geesje M Dallinga-Thie, Rindert de Vries, Wim J Sluiter and Arie van Tol

Objective

We tested whether in metabolic syndrome (MetS) subjects the ability of plasma to stimulate cellular cholesterol efflux, an early step in the anti-atherogenic reverse cholesterol transport pathway, is maintained despite low high-density lipoprotein (HDL) cholesterol.

Design

In 76 subjects with and 94 subjects without MetS based on the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria, we determined plasma (apo)lipoproteins, pre-β-HDL formation, phospholipid transfer protein (PLTP) activity, cholesterol esterification (EST), cholesteryl ester transfer (CET), adiponectin, and the ability of plasma from each subject to stimulate cholesterol efflux out of cultured fibroblasts obtained from a single donor.

Results

Apo E, PLTP activity, EST, and CET were higher (P=0.04 to <0.001), whereas adiponectin was lower in MetS subjects (P<0.01). Pre-β-HDL and pre-β-HDL formation were not different between subjects with and without MetS. Cellular cholesterol efflux to plasma from MetS subjects was slightly higher versus plasma from subjects without MetS (8.8±1.0 vs 8.5±0.9%, P=0.05), but the difference was not significant after age, sex, and diabetes adjustment. Cellular cholesterol efflux was positively related to pre-β-HDL formation, EST, PLTP activity, and apo E (P<0.05 for all by multiple linear regression analysis), without an independent association with MetS and diabetes status.

Conclusions

The ability of plasma from MetS subjects to promote fibroblast cholesterol efflux is not defective, although HDL cholesterol is decreased. Higher cholesterol esterification, PLTP activity, and apo E levels may contribute to the maintenance of cholesterol efflux in MetS.

Free access

Pauline Brummelman, Margriet G A Sattler, Linda C Meiners, Martin F Elderson, Robin P F Dullaart, Gerrit van den Berg, Janneke Koerts, Oliver Tucha, Bruce H R Wolffenbuttel, Alfonsus C M van den Bergh and André P van Beek

Objective

The hippocampus and prefrontal cortex (PFC) are important for memory and executive functioning and are known to be sensitive to radiotherapy (RT). Radiation dosimetry relates radiation exposure to specific brain areas. The effects of various pituitary RT techniques were studied by relating detailed dosimetry of the hippocampus and PFC to cognitive performance.

Methods

In this cross-sectional design, 75 non-functioning pituitary macroadenoma (NFA) patients (61±10 years) participated and were divided into irradiated (RT+, n=30) and non-irradiated (RT−, n=45) groups. The RT+ group (who all received 25 fractions of 1.8 Gy; total dose: 45 Gy) consisted of three RT technique groups: three-field technique, n=10; four-field technique, n=15; and five-field technique, n=5. Memory and executive functioning were assessed by standardized neuropsychological tests. A reconstruction of the dose distributions for the three RT techniques was made. The RT doses on 30, 50, and 70% of the volume of the left and right hippocampus and PFC were calculated.

Results

Cognitive test performance was not different between the four groups, despite differences in radiation doses applied to the hippocampi and PFC. Age at RT, time since RT, and the use of thyroid hormone varied significantly between the groups; however, they were not related to cognitive performance.

Conclusion

This study showed that there were no significant differences on cognitive performance between the three-, four-, and five-field RT groups and the non-irradiated patient group. A dose–response relationship could not be established, even with a radiation dose that was higher on most of the volume of the hippocampus and PFC in case of a four-field RT technique compared with the three- and five-field RT techniques.

Free access

Robin P F Dullaart, Gerrit van den Berg, Aafke M van der Knaap, Janneke Dijck-Brouwer, Geesje M Dallinga-Thie, Peter M J Zelissen, Wim J Sluiter and André P van Beek

Objective

GH replacement lowers total cholesterol and low-density lipoprotein cholesterol (LDL-C) in GH-deficient adults, but effects on high-density lipoprotein (HDL) cholesterol (HDL-C) are variable. Both GH and glucocorticoids decrease cholesteryl ester transfer protein (CETP) activity, which is important in HDL metabolism. We determined the extent to which the changes in HDL-C in response to GH replacement are predicted by the −629C>A CETP promoter polymorphism, and questioned whether this association is modified by concomitant glucocorticoid treatment.

Design and methods

A total of 91 GH-deficient adults (63 receiving glucocorticoids) were genotyped for the −629 CETP C>A polymorphism. Fasting serum lipids were measured before and after 1.2±0.4 years of GH treatment (Genotropin, Pfizer Inc., Stockholm, Sweden).

Results

In the whole group, total cholesterol and LDL-C decreased (P<0.05) after GH treatment, but the changes in HDL-C were not significant. In CC carriers receiving glucocorticoids (n=19), HDL-C rose by 0.15±0.25 mmol/l (P=0.02; P<0.03 from unchanged HDL-C in −629 AA+CA carriers on glucocorticoids and from CC homozygotes not receiving glucocorticoids). Multivariate regression analysis showed that individual changes in HDL-C were predicted by the CETP polymorphism (CC versus AA+CC, P=0.006) in glucocorticoid users, independently of baseline HDL-C and other variables including apolipoprotein E4 carrier status; an opposite association with the CETP polymorphism was found in patients not receiving glucocorticoids (P=0.053).

Conclusions

We suggest a common CETP variant-glucocorticoid treatment interaction concerning the effect of GH replacement on HDL-C. This may explain some of the reported variation in the HDL-C response to GH.

Free access

Edward Buitenwerf, Tijmen Korteweg, Anneke Visser, Charlotte M S C Haag, Richard A Feelders, Henri J L M Timmers, Letizia Canu, Harm R Haak, Peter H L T Bisschop, Elisabeth M W Eekhoff, Eleonora P M Corssmit, Nanda C Krak, Elise Rasenberg, Janneke van den Bergh, Jaap Stoker, Marcel J W Greuter, Robin P F Dullaart, Thera P Links and Michiel N Kerstens

Background

A substantial proportion of all pheochromocytomas is currently detected during the evaluation of an adrenal incidentaloma. Recently, it has been suggested that biochemical testing to rule out pheochromocytoma is unnecessary in case of an adrenal incidentaloma with an unenhanced attenuation value ≤10 Hounsfield Units (HU) at computed tomography (CT).

Objectives

We aimed to determine the sensitivity of the 10 HU threshold value to exclude a pheochromocytoma.

Methods

Retrospective multicenter study with systematic reassessment of preoperative unenhanced CT scans performed in patients in whom a histopathologically proven pheochromocytoma had been diagnosed. Unenhanced attenuation values were determined independently by two experienced radiologists. Sensitivity of the 10 HU threshold was calculated, and interobserver consistency was assessed using the intraclass correlation coefficient (ICC).

Results

214 patients were identified harboring a total number of 222 pheochromocytomas. Maximum tumor diameter was 51 (39–74) mm. The mean attenuation value within the region of interest was 36 ± 10 HU. Only one pheochromocytoma demonstrated an attenuation value ≤10 HU, resulting in a sensitivity of 99.6% (95% CI: 97.5–99.9). ICC was 0.81 (95% CI: 0.75–0.86) with a standard error of measurement of 7.3 HU between observers.

Conclusion

The likelihood of a pheochromocytoma with an unenhanced attenuation value ≤10 HU on CT is very low. The interobserver consistency in attenuation measurement is excellent. Our study supports the recommendation that in patients with an adrenal incidentaloma biochemical testing for ruling out pheochromocytoma is only indicated in adrenal tumors with an unenhanced attenuation value >10 HU.