Koemelk verstoort opname levothyroxine + abstracten

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Lid geworden op: 08 nov 2014, 17:53

Koemelk verstoort opname levothyroxine + abstracten

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Koemelk verstoort de opname van levothyroxine medicatie.
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April 2, 2017
Cow's milk interferes with absorption of thyroid supplement levothyroxine

Taking the common oral thyroid hormone medication levothyroxine with a glass of cow's milk significantly decreases the body's ability to absorb the drug, a preliminary study finds. Results will be presented Sunday at ENDO 2017, the Endocrine Society's 99th annual meeting in Orlando, Fla.

"These findings support previous research showing that calcium supplements can interfere with levothyroxine absorption," said principal investigator Deborah Chon, M.D., an endocrinology fellow at the UCLA David Geffen School of Medicine and the VA (Veterans Affairs) Greater Los Angeles Healthcare System, Los Angeles, Calif. "Decreased absorption means that patients may not get the full dose of thyroid hormone that they are prescribed."

Although it makes sense that milk, which contains calcium, might interfere with levothyroxine absorption, no study has proved that it does until now, according to Chon.

Levothyroxine is prescribed for patients with an underactive thyroid, called hypothyroidism, to replace the natural thyroid hormone thyroxine (T4) that is too low, or for patients with thyroid cancer, to suppress their thyroid stimulating hormone levels. In 2014, levothyroxine was the most commonly prescribed medication in the U.S., a survey from the IMS Institute for Healthcare Informatics (now QuintilesIMS) found.

Chon and fellow investigators studied 10 adults (six men and four women), with an average age of 33.7 years, who had no known thyroid disease and had normal thyroid hormone function at the start of the study. No one was allergic to cow's milk or levothyroxine, and none of the women were pregnant or using birth control pills.

Participants fasted overnight before each of two study visits, spaced a month apart. At one visit, participants took 1,000 micrograms of oral levothyroxine alone and at the other visit, they took the same dose concurrently with 12 ounces of 2 percent milk. Before dosing and one, two, four and six hours after ingestion of levothyroxine, participants gave blood samples for measurement of their total T4 levels. Chon said they tested with generic levothyroxine, which most of their patients are taking.

The investigators measured the levothyroxine absorption as the concentration of total T4 in the blood plotted on a graphic curve against time after drug administration, called area under the curve. Over the six hours after the participants took levothyroxine, those who consumed milk at the same time as the medicine had significantly lower total T4 absorption than when they took the drug alone: average area under the curve of 67.3 versus 73.5.

The manufacturer of a brand of levothyroxine recommends that the medication be taken preferably on an empty stomach, 30 to 60 minutes before eating food or taking other medications or vitamins.

"The main message of this study is that patients managed with thyroid hormone replacement therapy should be advised to avoid taking levothyroxine simultaneously with cow's milk, given its interference," Chon said.


Bron: Medical Express


Op de website van Endocrine Society:
Concurrent Milk Ingestion Decreases Oral Levothyroxine Absorption

Deborah Chon*1, Tamar Reisman2, Jane Weinreb3, Jerome M Hershman1 and Angela M. Leung4
1UCLA David Geffen School of Medicine; VA Greater Los Angeles Healthcare System, Los Angeles, CA, 2UCLA David Geffen School of Medicine; VA Greater Los Angeles Healthcare System, 3David Geffen School of Medicine at UCLA; VA Greater Los Angeles Healthcare System, Los Angeles, CA, 4UCLA David Geffen School of Medicine, Los Angeles, CA

Background:
Levothyroxine is used for the physiologic replacement of thyroid hormone in patients with hypothyroidism and for serum TSH suppression in patients with thyroid cancer. In 2011, levothyroxine was the second most commonly prescribed medication in the United States, and frequent dose adjustments have been demonstrated to be a costly burden to the national healthcare system (1-2).
Several studies have shown that certain foods and medications, such as calcium supplements, can interfere with levothyroxine absorption (3-5). There are no published studies specifically investigating the effect of cow’s milk, a common breakfast staple, on the absorption of levothyroxine. Cow’s milk contains approximately 450 mg of elemental calcium per 12 oz. serving.

Materials and Methods:
To determine the possible effect of cow’s milk ingestion, we measured levothyroxine absorption with and without concurrent milk consumption.
Pharmacokinetic studies were conducted in healthy adults without allergies to milk or levothyroxine, and who were not pregnant nor using oral contraceptives.
All subjects had no history of known thyroid disease and a normal serum TSH concentration at baseline.
Following an overnight fast, serum total thyroxine T4 (TT4) concentrations were measured at baseline and at 1, 2, 4, and 6 hours after ingestion of 1,000 μg of oral levothyroxine alone or when co-administered with 12 oz. of milk (2% fat). There was a four-week washout period between the two study visits.

Results:
Ten subjects (mean age 33.7±10.2 years, 60% male) completed the study. The serum total T4 absorption over six hours, calculated as area under the curve (AUC), was significantly lower in those who consumed cow’s milk concurrently with levothyroxine, compared to those who took the levothyroxine alone (mean±SD: 67.26±12.13 vs.73.48±16.96; p = 0.02).

Conclusions:
This is the first study to demonstrate that concurrent cow’s milk ingestion reduces oral levothyroxine absorption.
The findings support previous literature showing the interference of elemental calcium with oral levothyroxine absorption.
Patients managed with thyroid hormone replacement therapy should be advised to avoid taking levothyroxine simultaneously with cow’s milk.

Zie:
https://plan.core-apps.com/tristar_endo ... 74bc2ef0b1



Abstracten:
Een lange overzichtslijst van abstracte artikelen - gepresenteerd op deze ENDO bijeenkomst.
Bijvoorbeeld:
Declining FT4 Concentrations Following Cranial Irradiation: Indications for Early Development of Mild Central Hypothyroidism

Number: SUN 025
Category: Pediatric Endocrinology
Authors: L. van Iersel

L. van Iersel*1, S.C. Clement1, A.Y.N. Schouten-van Meeteren2, A.M. Boot3, H.L. Claahsen-van der Grinten4, B. Granzen5, K.S. Han6, G.O. Janssens7, E.M. Michiels8, A.S.P. van Trotsenburg2, W.P. Vandertop9, D.G. van Vuurden10, H.N. Caron2, L.C.M. Kremer2 and H.M. van Santen1
1 Wilhelmina Children’s Hospital, University Medical Center Utrecht, Utrecht, Netherlands, 2 Emma Children’s Hospital, Academic Medical Center, Amsterdam, Netherlands,
3 University Medical Center Groningen, Groningen, Netherlands,
4 Amalia Children's Hospital, Radboud University Medical Centre, Nijmegen, Netherlands,
5 Maastricht University Medical Center, Maastricht, Netherlands,
6 University Medical Center Utrecht, Utrecht, Netherlands,
7 Princess Maxima Centre for Pediatric Oncology, University Medical Center Utrecht, Utrecht, Netherlands,
8 Sophia Children's Hospital, Erasmus Medical Center, Rotterdam, Netherlands,
9 Neurosurgical Center Amsterdam, Academic Medical Center, and VU University Medical Center, Amsterdam, Netherlands,
10V U University Medical Center, Amsterdam, Netherlands

Background:
After exposure to cranial radiotherapy (cRT), hypothalamic-pituitary (HP) disorders are frequently observed in childhood brain tumor survivors (CBTS). It has been reported that the time to develop HP disorders varies, with a short lag time for GH deficiency (GHD) especially when compared to central hypothyroidism (CeH). (1, 2) In clinical practice, however, a decline in FT4 concentration in CBTS is frequently observed prior to or shortly after the diagnosis GHD. Declining FT4 concentrations with (inadequate) normal-low TSH concentrations in CBTS may indicate radiation damage to TSH secreting cells.
Hypothesis: The decline in FT4 concentration, often observed prior to or shortly after the diagnosis of GHD in CBTS who received cRT, can be validated in a large nationwide cohort.

Methods:
Inclusion criteria for the nationwide cohort study were: patients with a brain tumor diagnosed between 2002 and 2012, surviving >2 years after diagnosis and treated with cRT. All CBTS who developed GHD were included and CBTS with primary hypothyroidism were excluded. GHD was defined as an abnormal peak value of GH in one or two GH stimulation tests. The paired sample T-test was used to compare median FT4 concentrations at start of tumor treatment versus the median FT4 concentrations at diagnosis of GHD versus the median first FT4 concentrations after starting GH treatment.

Results:
Seventy-three CBTS had been diagnosed with GHD and were included for this study. Twenty-one CBTS (28.8%) were diagnosed with CeH prior to the diagnosis of GHD and therefore received treatment with thyroxine (T4). In 52 of the 73 CBTS (71.2%) FT4 concentrations were longitudinally analysed. GHD was diagnosed after a median follow-up time of 2.4yr after tumor diagnosis. The total median dose of cRT was 54Gy (range 15-72Gy). Median FT4 concentrations declined from 15.4 pmol/l after the start of tumor treatment to 14.0 pmol/l (P<0.01, CI 0.79-2.39) at diagnosis of GHD. Forty-five of the 52 CBTS started on GH treatment, while seven did not (yet) receive GH treatment due to tumor or patient related reasons. After starting treatment with GH, a further decline of median FT4 concentration was seen (11.3 pmol/L (p<0.01, CI 1.08-3.35) after a median follow-up time of 0.27yr (range 0.07-2.16yr). In 25 of these 45 CBTS, treatment with T4 was subsequently started. In the 20 CBTS who did not receive T4 treatment, FT4 concentrations stabilized compared to values prior to GH treatment.

Conclusion:
A decline in FT4 concentration prior to or shortly after the diagnosis GHD is confirmed in a large nationwide cohort of CBTS. This may indicate that (mild) CeH occurs earlier than currently suspected and points to possible equal radiosensitivity of the TSH- and GH-secreting cells of the pituitary gland. Further studies are needed to unravel the exact radiosensitivity of the different cells in the pituitary gland and the clinical consequences of (mild) CeH in CBTS

https://plan.core-apps.com/tristar_endo ... 5444cca1ba

Lijst abstracte artikelen:
https://plan.core-apps.com/tristar_endo17/abstracts


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