Tokuchi et al. Asia Pac Fam Med (2016) 15:4
DOI 10.1186/s12930-016-0029-8

Asia Pacific Family Medicine
Open Access

CASE REPORT

Low carbohydrate diet‑based
intervention for obstructive sleep apnea
and primary hypothyroidism in an obese
Japanese man
Yoshio Tokuchi1* , Yayoi Nakamura1, Yusuke Munekata2 and Fumio Tokuchi1

Abstract
Background: Obesity is a major risk factor for obstructive sleep apnea (OSA), and weight loss is necessary in theoverall management of obese patients with OSA. However, primary care physicians can provide only limited weightloss with lifestyle interventions, usually reducing a patient’s body weight by only 2.5 kg or less after 6–18 months.
Case presentation: A 45-year-old Japanese man was referred to our clinic owing to obesity, daytime sleepiness,and snoring during sleep. His weight was 130.7 kg and his body mass index (BMI) was 41.0 kg/m2. He underwent
polysomnography, which revealed OSA with an apnea–hypopnea index of 71.2 events/h (normal, <5 events/h). His
laboratory results were as follows: thyroid stimulating hormone, >500 μIU/mL; free triiodothyronine, 1.4 pg/mL; freethyroxine, <0.15 ng/dL; thyroid peroxidase antibody, 10 IU/mL; thyroglobulin antibody, >4000 IU/mL; total cholesterol(TC), 335 mg/dL; high-density lipoprotein cholesterol, 45 mg/dL; triglycerides (TGs), 211 mg/dL; low-density lipoprotein cholesterol, 248 mg/dL; fasting blood sugar, 86 mg/dL; and glycated hemoglobin (HbA1c), 6.1 %. These results
showed that he also had primary hypothyroidism (Hashimoto’s disease). Continuous positive airway pressure (CPAP),
levothyroxine replacement, and a low-carbohydrate diet (LCD) were initiated. CPAP use and a euthyroid condition
induced by 175 μg/day levothyroxine allowed the patient to proactively reduce his body weight. After 18 months, thepatient achieved a weight reduction of 32.4 kg (25 % of his initial weight) and a BMI reduction of 10.2 kg/m2, as well as
improved laboratory results, including an HbA1c level of 5.3 %, TC level of 194 mg/dL, and TG level of 89 mg/dL.
Conclusion: An LCD may be an effective intervention for weight loss in obese Japanese patients with OSA. Further
studies are needed to investigate the weight loss effect of an LCD compared with a conventional calorie-restricted
diet. Hopefully, this case report will help to improve the management of obese Asian patients with OSA who typicallyconsume a higher amount of carbohydrates.
Keywords: Obstructive sleep apnea, Continuous positive airway pressure, Low-carbohydrate diet, Obesity,
Hypothyroidism, Levothyroxine replacement
BackgroundObesity is a major risk factor for obstructive sleep
apnea (OSA) [1], and weight loss is necessary in theoverall management of obese patients with OSA. However, primary care physicians can provide only limited*Correspondence: yoshio‑tokuchi@hokkaido.med.or.jp
1
Tokuchi Naika Clinic, 3‑6, Iwamizawa, Hokkaido 068‑0023, Japan
Full list of author information is available at the end of the article

weight loss by medical therapy alone. Previous trials, inwhich primary care physicians offered lifestyle counseling, achieved a weight loss of only 2.5 kg or less after
6–18 months [2, 3]. In addition, intensive medical therapy or enhanced weight loss counseling for patients withobesity has been shown to achieve a mean weight loss of
4.3–5.1 kg after 2–3 years [1, 2, 4]. In contrast, continuous positive airway pressure (CPAP)—the standard treatment for OSA—may actually increase the body weight of© 2016 The Author(s). This article is distributed under the terms of the Creative Commons Attribution 4.0 International License(http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium,provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license,
and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/
publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Tokuchi et al. Asia Pac Fam Med (2016) 15:4

patients [5]. On the other hand, hypothyroidism can beassociated with OSA [6], and some symptoms, such as
daytime sleepiness, fatigue, and lethargy, overlap for bothdiseases.
Here, we describe an obese Japanese man with OSA
and primary hypothyroidism who was treated with CPAP,
levothyroxine replacement, and a low-carbohydrate diet(LCD) and achieved a weight reduction of 32.4 kg (25 %of his initial weight) and a body mass index (BMI) reduction of 10.2 kg/m2 after 18 months.

Case presentation
In January 2014, a 45-year-old Japanese man was referredto our clinic owing to obesity, daytime sleepiness, andsnoring during sleep. His Epworth Sleepiness Scale score
was 10 points. He underwent overnight diagnostic polysomnography in February 2014. Upon admission, hisheight was 178.6 cm, weight was 130.7 kg, abdominal circumference was 122 cm, and BMI was 41.0 kg/m2. Physical examination showed that the thyroid gland was not
palpable. His serum levels of creatine kinase and creatinine were elevated at 1581 U/L and 1.46 mg/dL, respectively, while his other laboratory results were as follows:
aspartate aminotransferase, 57 U/L; alanine aminotransferase, 49 U/L; lactate dehydrogenase, 353 U/L; totalcholesterol (TC), 335 mg/dL; high-density lipoproteincholesterol, 45 mg/dL; triglycerides (TGs), 211 mg/dL;
low-density lipoprotein cholesterol, 248 mg/dL; fastingblood sugar, 86 mg/dL; glycated hemoglobin (HbA1c),
6.1 %; thyroid-stimulating hormone (TSH), >500 μIU/
mL; free triiodothyronine, 1.4 pg/mL; free thyroxine, <0.15 ng/dL; thyroid peroxidase antibody, 10 IU/
mL; and thyroglobulin antibody, >4000 IU/mL (Table 1).
Blood samples were evaluated using routine methods at
Sapporo Clinical Laboratory Inc. (Sapporo, Hokkaido,
Japan). Based on these results, indicating hypothyroidism and thyroglobulin antibody positivity, the patient wasdiagnosed with severe primary hypothyroidism (Hashimoto’s thyroiditis). His dyslipidemia and impaired glucose tolerance were considered as secondary changes
due to primary hypothyroidism and obesity. Because
polysomnography showed an apnea–hypopnea index(AHI) of 71.2 events/h (normal, <5 events/h) and a minimal SpO2 of 60 %, he also was diagnosed with severe
OSA associated with autoimmune hypothyroidism.
Therefore, in the beginning of March 2014, nasal CPAP(ICON+Auto, auto-adjusting CPAP; Fisher & Paykel
Healthcare Limited, Auckland, New Zealand; minimalpressure, 4.0 cmH2O; maximal pressure, 18.0 cmH2O)
and low-dose levothyroxine (12.5 μg/day) were initiated.
Upon initiation of the CPAP therapy, the patient was
informed that he would have to continue with the CPAP
therapy unless his body weight decreased sufficiently.

Page 2 of 4

Table 1 Laboratory results of blood samples on admission
CBC
WBCs
RBCs

5500 × 103/μL

452 × 104/μL

Hgb

14.1 g/dL

PLTs

25.6 × 104/μL

GlucoseFBS

86 mg/dL

HbA1c

6.1 %

LipidsTC

335 mg/dL

HDL-C

45 mg/dL

TGs

211 mg/dL

LDL-C

248 mg/dL

Thyroid
TSH>500 μIU/mL

fT4<0.15 ng/dL

fT3

1.4 pg/mL

Tg antibody>4000 IU/mL

TPO antibody

10 IU/mL

BiochemistryTP

6.9 g/dL

TB

0.8 mg/dL

AST

57 U/LALT

49 U/L

LDH

353 U/LALP

209 U/L

γGTP

75 U/L

CK

1581 U/L

Cr

1.46 mg/dL

UA

6.9 mg/dL

BUN

11.4 mg/dL

Na

139 mEq/L

K

4.1 mEq/L

Cl

98 mEq/L

CRP

0.17 mg/dL

Abnormal findings are italicized
ALP alkaline phosphatase, ALT alanine aminotransferase, AST aspartate
aminotransferase, BUN blood urea nitrogen, CBC complete blood count, CK
creatine kinase, Cl chloride; Cr creatinine, CRP C-reactive protein, FBS fastingblood sugar, fT3 free triiodothyronine, fT4 free thyroxine, γGTP gamma-glutamyltransferase, HbA1c glycated hemoglobin, HDL-C high-density lipoproteincholesterol, Hgb hemoglobin, K potassium, LDH lactate dehydrogenase, LDL-C
low-density lipoprotein cholesterol, Na sodium, PLTs platelets, RBCs red blood
cells, TB total bilirubin, TC total cholesterol, Tg thyroglobulin, TGs triglycerides,
TP total protein, TPO thyroperoxidase, TSH thyroid-stimulating hormone, UA uricacid, WBCs white blood cells

In April 2014, the patient’s body weight had decreased
to 125.2 kg, and post-CPAP polysomnography indicatedimproved OSA (AHI, 2.8 events/h; minimal SpO2, 88 %).
A monthly follow-up visit was scheduled to check his
body weight and adherence to CPAP. The memory stickof the CPAP machine showed that he used CPAP for

Tokuchi et al. Asia Pac Fam Med (2016) 15:4

Page 3 of 4

an average of 6 h per night, 6 days a week, and that hehad an AHI of approximately 2.0 events/h. In the courseof gradually increasing the dose of levothyroxine, thepatient reportedly felt better and had recovered from his
fatigue and lethargy.
To address his weight loss as a priority, an LCD wasinitiated in July 2014 [7]. Yamada et al. [8] reported thebenefits of a non-calorie-restricted LCD with the amountof carbohydrates limited to 70–130 g/day for Japanesepatients with type 2 diabetes. The patient consumed 50 gof white rice per meal in addition to vegetables, fish, eggs,
and meat in the morning and at noon; however, he did
not eat rice, noodles, or other carbohydrates at night.
In February 2015, the dose of 175 μg/day levothyroxineappeared to maintain a euthyroid state (TSH, 0.75 μIU/mL), and his other laboratory results were within normal limits, including an HbA1c level of 5.3 %, TC level of
194 mg/dL, and TG level of 89 mg/dL.
Finally, in July 2015, the patient’s body weight reached98.3 kg, a reduction of 32.4 kg (25 % of his initial bodyweight), while his BMI decreased from 41.0 to 30.8 kg/m2.
Figure 1 shows changes in his body weight and TSH level
over time. The patient felt motivated by the prospect of
discontinuing the CPAP therapy, and was encouraged by
the consistent weight loss at the monthly clinical visits.
He also wanted to continue with the LCD because he did
not find it difficult.

Discussion
The course of this patient provided two important clinical suggestions. First, this obese Japanese man with OSA
achieved a weight loss of 32.4 kg (25 % of his initial bodyweight) by medical therapy alone. Second, an LCD may
be an effective intervention for obese Japanese patientswith OSA.
There are three potential mechanisms for this patient’s
successful weight loss. First, CPAP was able to control

120

500

100

400

80
300

60
Body weight40

Jul-15100

Jun-15Mar-15Jan-15

Feb-15

Dec-14Oct-14

Nov-14

Sep-14Jul-14Aug-14Jun-14Apr-14May-14Feb-14Mar-140

Apr-15

TSH

20

200

TSH level ( μIU /mL)

600

May-15

Body weight (kg)Clinical course
1400Fig. 1 Changes in the patient’s body weight and thyroid-stimulating
hormone (TSH) level over time

his sleepiness effectively. Second, his primary hypothyroidism was corrected to a euthyroid state with 175 μg/
day levothyroxine. Third, an LCD was initiated as dietary therapy. Therefore, both OSA and primary hypothyroidism were treated simultaneously in this patient.
He recovered from his fatigue and lethargy, thus enabling him to reduce his body weight more proactively. In
developed Western countries, bariatric surgery can be
performed for weight loss in patients with obesity [1, 4].
Such surgeries have been shown to achieve a weight lossof 24.5–27.8 kg (20.6–24.5 % of initial body weight) after
2–3 years [1, 4]. Therefore, the weight loss of this patient
after 2 years was similar to that observed in those whohave undergone bariatric surgery.
An LCD is an effective intervention for weight loss inpatients with obesity [7]. Japanese individuals typicallyconsume a higher amount of carbohydrates comparedwith Western populations, obtaining approximately
60 % of their total energy intake from carbohydrates [9].
Therefore, an LCD may have a superior weight loss effectin obese Japanese patients. As far as we know, this is thefirst case in which an LCD was initiated in an obese Japanese patient with OSA. An LCD was introduced in thiscase in July 2014. His weight loss from June to July was
1.4 kg, whereas, from July to August, his weight loss was
5.1 kg. Thus, the LCD seemed to accelerate his weightloss. His glucose and lipid metabolism also improved
without diabetes or hyperlipidemia medication. In aprevious large long-term observational study in Japan,
a usual LCD was found to be significantly inversely
associated with cardiovascular and total mortality [9].
Therefore, an LCD could allow Japanese primary care
physicians to achieve clinically meaningful weight loss
in their obese patients, which they might not be able toaccomplish otherwise. However, because CPAP may
increase the body weight of obese patients with OSA [5,10], additional therapy for weight loss is required. Furthermore, weight loss after levothyroxine replacement for
hypothyroidism does not always occur [11, 12]. In a previous study, levothyroxine achieved a weight loss of only
4.3 kg (from an average of 83.7–79.4 kg) after 1 year [13].
Moreover, such weight loss occurred due to decrease inlean body mass, whereas fat mass did not decline [13].
This suggests that the weight loss after levothyroxine
replacement was due to loss of excess body water associated with untreated myxedema [13]. Thus, levothyroxine
replacement alone may not achieve an adequate weightloss in patients with hypothyroidism.

Conclusion
We described an obese Japanese man with OSA andprimary hypothyroidism who achieved a weight lossof 32.4 kg (25 % of his initial body weight) by medical

Tokuchi et al. Asia Pac Fam Med (2016) 15:4

therapy alone. We further demonstrated that an LCD
may be an effective intervention for weight loss in obese
Japanese patients with OSA. Further studies are needed
to investigate the weight loss effect of an LCD comparedwith a conventional calorie-restricted diet. Hopefully,
this case report will help to improve the management ofobese Asian patients with OSA who typically consume ahigher amount of carbohydrates.
Abbreviations
AHI: apnea–hypopnea index; BMI: body mass index; CPAP: continuous positive
airway pressure; HbA1c: glycated hemoglobin; LCD: low-carbohydrate diet;
OSA: obstructive sleep apnea; TC: total cholesterol; TGs: triglycerides.
Authors’ contributions
YT managed the patient and drafted the manuscript. YN performed thethyroid ultrasonography and advised the management of the patient. YM
analyzed the sleep studies and managed the CPAP at the patient’s home.
FT supervised both the management of the patient and the drafting of themanuscript. All authors read and approved the final manuscript.
Author details
1
Tokuchi Naika Clinic, 3‑6, Iwamizawa, Hokkaido 068‑0023, Japan. 2 Hokkaido
Air Water Inc., Kikusui 5‑2‑3‑12, Shiroishi‑ku, Sapporo, Hokkaido 003‑0805,
Japan.
Acknowledgements
The authors wish to thank Drs. K. Ebe (Takao Hospital) and J. Kanaya (Sapporo
Masui Clinic) for their helpful advice and discussion. They also wish to thank
Editage (www.editage.jp) for providing its English language editing service.
Competing interests
The authors declare that they have no competing interests.
Availability of data and materials
The datasets supporting the conclusions of this article are included within thearticle and its additional files.

Page 4 of 4

References
1. Dixon JB, Schachter LM, O’Brien PE, Jones K, Grima M, Lambert G, et al.
Surgical vs conventional therapy for weight loss treatment of obstructive
sleep apnea: a randomized controlled trial. JAMA. 2012;308:1142–9.
2. Wadden TA, Volger S, Sarwer DB, Vetter ML, Tsai AG, Berkowitz RI, et al. A
two-year randomized trial of obesity treatment in primary care practice.
N Engl J Med. 2011;365:1969–79.
3. Kanke S, Kawai T, Takasawa N, Mashiyama Y, Ishii A, Kassai R. Interventions
for body weight reduction in obese patients during short consultations:an open-label randomized controlled trial in the Japanese primary caresetting. Asia Pac Fam Med. 2015;14:5.
4. Schauer PR, Bhatt DL, Kirwan JP, Wolski K, Brethauer SA, Navaneethan SD,
et al. Bariatric surgery versus intensive medical therapy for diabetes—
3-year outcomes. N Engl J Med. 2014;370:2002–13.
5. Drager LF, Brunoni AR, Jenner R, Lorenzi-Filho G, Benseñor IM, Lotufo
PA. Effects of CPAP on body weight in patients with obstructive sleep
apnoea: a meta-analysis of randomised trials. Thorax. 2015;70:258–64.
6. Attal P, Chanson P. Endocrine aspects of obstructive sleep apnea. J Clin
Endocrinol Metab. 2010;95:483–95.
7. Shai I, Schwarzfuchs D, Henkin Y, Shahar DR, Witkow S, Greenberg I, et al.
Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. N
Engl J Med. 2008;359:229–41.
8. Yamada Y, Uchida J, Izumi H, Tsukamoto Y, Inoue G, Watanabe Y, et al. A
non-calorie-restricted low-carbohydrate diet is effective as an alternative
therapy for patients with type 2 diabetes. Intern Med. 2014;53:13–9.
9. Nakamura Y, Okuda N, Okamura T, Kadota A, Miyagawa N, Hayakawa
T, et al. Low-carbohydrate diets and cardiovascular and total mortality in Japanese: a 29-year follow-up of NIPPON DATA80. Br J Nutr.
2014;112:916–24.
10. Tachikawa R, Ikeda K, Minami T, Matsumoto T, Hamada S, Murase K, et al.
Changes in energy metabolism after continuous positive airway pressurefor obstructive sleep apnea. Am J Respir Crit Care Med. 2016 Mar 1. [Epubahead of print].
11. Lee SY, Braverman LE, Pearce EN. Changes in body weight after treatment of primary hypothyroidism with levothyroxine. Endocr Pract.
2014;20:1122–8.
12. Skjodt NM, Atkar R, Easton PA. Screening for hypothyroidism in sleep
apnea. Am J Respir Crit Care Med. 1999;160:732–5.
13. Karmisholt J, Andersen S, Laurberg P. Weight loss after therapy of hypothyroidism is mainly caused by excretion of excess body water associatedwith myxoedema. J Clin Endocrinol Metab. 2011;96:E99–103.

Consent for publication
Written informed consent was obtained from the patient for publication ofthis case report and any accompanying images.
Received: 9 June 2016 Accepted: 29 July 2016

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