A Case of Peripheral Precocious Puberty May Be Caused by a Diet Containing Phytosterols in a 20-Month-Old Boy

Introduction

Precocious puberty is defined as the onset of secondary sexual characteristics development before 8 years in girls and 9 years in boys [1]. Precocious puberty is classified into central precocious puberty and peripheral precocious puberty (PPP). Central precocious puberty is dependent on activation of the hypothalamic-pituitary-gonadal axis, while PPP, which results from peripheral production of sex steroids, is independent of activation of the hypothalamic-pituitary-gonadal axis. The secondary sexual characteristic development, progression of puberty, and sequence of adolescent events in PPP may be significantly different from normal pubertal development [2]. PPP often appears among boys, and its etiologies are diverse, both congenital, such as congenital adrenocortical hyperplasia, McCune-Albright syndrome, and familial testotoxicosis, and acquired. Some tumors can secrete sex hormones, including adrenocortical tumors, gonadal tumors, and tumors that can secrete human chorionic gonadotropin, and are common acquired factors leading to PPP. In recent years, cases of PPP in children caused by exogenous steroids have been reported. However, PPP caused by substances contained in a daily diet flavoring is relatively rare. In the present study, we describe a case of PPP due to long-term and excessive intake of a phytosterol-containing diet in a 20-month-old boy.

Case Presentation

A 20-month-old boy was referred to the Department of Endocrinology and Metabolism of Shanghai Children’s Medical Center in October 2020, who came to see a doctor because of acne, hairiness, increased penis size, and coarse voice. The case was the first singleton born to a physically healthy and non-consanguineous couple by natural delivery at full-term, with a birth weight of 2,400 g. Recently, he showed language retardation and accelerated growth (86.5 cm tall 16 months old and 93 cm tall 20 months old). Since he was 5 months old, two cans of face cream have been used for repeated eczema. Before coming to our hospital, the patient went to two other hospitals for treatment. The patient’s mother reported that the boy had taken chicken essence seasoning for every meal since he was 6 months old, with a daily intake of about 15 g. There was no fever, vomiting, diarrhea, or other discomforts on the onset of the symptoms.

On physical examination, the patient’s length was 93 cm (1.88 SD above the mean for the sex and age [3]), and the weight was 18.2 kg (4.34 SD above the mean for the sex and age [3]). His muscles were developed, and the body fat distribution was decreased. Acne-like papules in the size of rice grains could be seen on the face and trunk, mainly on the face, red in color, with abscesses at the tip (Fig. 1a). The skin on the abdomen was darkly pigmented (Fig. 1b). Increased hairs were distributed in the forehead, back of the neck, upper limbs, both sides of the thighs, and lumbosacral region (Fig. 1c). He was found to have pigmentation on both nipples and areola. The breast tissue can be touched bilaterally, and the size is about 0.5 × 1 cm (Tanner stage of 2). Genitourinary examination showed that his two-sided testicles had descended to the scrotum with a volume of about 2 mL. The hyperpigmented penis was 5 cm (mean ± standard deviation for 2 years old: 3.54 ± 0.34 cm [4]) in length and 1.8 cm in diameter. Pubic hair can be seen at the root of the penis, reaching at the Tanner stage of 2. The clinical characteristics of this patient are shown in Table 1.

Open multimedia modal

Open multimedia modal

Biochemical examinations showed that the patient had damaged liver function (ALT 121 U/L, reference range: 0–55 U/L, AST 87 U/L, reference range: 5–34 U/L), abnormal blood lipid (increased total cholesterol [10.03 mmol/L, reference range: 0.00–5.20 mmol/L], triglyceride [3.47 mmol/L, reference range: <2.26 mmol/L], and low-density lipoprotein cholesterol [8.06 mmol/L, reference range: <3.37 mmol/L]) and increased the number of white blood cells. Hormone detection (Table 2) revealed that luteinizing hormone (LH), follicle-stimulating hormone (FSH), dihydrotestosterone, and androstenedione were decreased. The levels of estradiol (E2) and testosterone (T) were increased. Cortisol and ACTH rhythms and concentrations were normal (Table 3). In addition, the low-dose dexamethasone suppression test was negative. For the oral glucose tolerance test, after the analysis of the results, there was no insulin resistance (Table 4). The levels of tumor biomarkers (alpha fetoprotein, carcinoembryonic antigen, carbohydrate antigen 199) were also in the normal reference ranges.

Open multimedia modal

Open multimedia modal

Open multimedia modal

The imaging examination showed there were no obvious abnormalities in adrenal ultrasound and adrenal enhanced computed tomography (CT). The thyroid ultrasound test revealed normal as well. An abdominal ultrasound examination revealed that the liver was enlarged. Pituitary magnetic resonance imaging (MRI) showed pituitary hyperplasia, and skull MRI showed pituitary hyperplasia and uneven signal, and the sellar diaphragm was raised. Further sellar diaphragm-enhanced MRI showed no space occupying lesion. No abnormality was found in the positron emission tomography-computed tomography examination. The bone age (based on the X-rays of the left-hand bone) was 5.5 years old, which was much older than the chronological age. The chromosome karyotype of the patient was 46XY, and the results of the whole exon and Sanger sequencing of the CYP21A2 gene were normal and inconsistent with the clinical features. The cream and chicken essence seasoning were analyzed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS) to detect whether there were exogenous steroids. A kind of phytosterol (avenasterol/clerosterol/chondrillasterol) with the molecular formula C₂₉H₄₈O was found in chicken essence seasoning; the chromatogram (Fig. 2a) shows that retention time is 1.64 min, peak area (AA) is 946,850, and the signal to noise ratio (S/N) is 1,319, and the mass spectrum (Fig. 2b) shows that the mass-to-charge ratio (m/z) is 413.3761. No hormones and steroids were found in the cream. For the chromatographic conditions, the extraction samples were analyzed using a Q Exactive plus mass spectrometer (ThermoFisher Scientific, Waltham, MA, USA) linked to an Ultimate 3000 UPLC (Dionex, Sunnyvale, CA, USA), and a hydrophilic pHILIC column (150 mm × 2.1 mm, 5 µm, Merck) was used for chromatographic separation. For the MS acquisition, the Q-Exacitve plus spectrometer with electrospray ionization was operated in the data-dependent acquisition mode using Xcalibur 4.0.27 software (ThermoFisher Scientific). The sample was detected in full scan mode with positive and negative switching scan.

Open multimedia modal

The patient was treated with compound glycyrrhizin tablets [5] (12.5 mg oral administration, three times a day) to protect the liver, ursodeoxycholic acid tablets [6] (200 mg oral administration, once a day) to reduce free cholesterol, and cetirizine hydrochloride tablets for anti-allergy treatment. At the same time, the patient was advised to avoid chicken essence seasoning food and cream and to monitor the level of sex hormones dynamically. After stopping the use of cream and avoiding the chicken essence seasoning diet for 1 month, examinations at the clinic follow-up showed that the level of E2 and T declined dramatically. At a follow-up after 10 months, the concentration of E2 decreased to a normal level. The decline trends of LH, FSH, E2, and T levels are shown in Figure 3. Furthermore, all of the clinical symptoms of the patient improved. We can see the improvements in facial acne (Fig. 1d), the recovery of skin color (Fig. 1e), the regression of whole-body hair, and the growth and development returned to normal. The differences between admission and 10 months later at clinical follow-up were compared and shown in Figure 1.

Open multimedia modal

Discussion

The developmental procedure of peripheral precocious puberty is not completely consistent with that of normal puberty. The absence of testicular enlargement but the penis and pubic hair developed in this case, in combination with low gonadotrophins (LH, FSH) and high sex hormones (E2, T), confirmed a gonadotrophin-independent process. The normal cortisol rhythm and baseline 17-OH-P and ACTH concentration, along with the normal sequencing results of the CYP21A2 gene in the patient, did not support the diagnosis of congenital adrenal hyperplasia secondary to 21-hydroxylase deficiency. The possibility of adrenal tumors can also be excluded by adrenal image and biochemical examination of tumor biomarkers. The results of the MRI examination of the pituitary and skull were not consistent with the manifestations of intracranial tumors. According to some research, estrogen can stimulate pituitary cell proliferation in the pituitary gland through its receptor-mediated signaling pathway, leading to pituitary hyperplasia [7]. We speculated that the pituitary hyperplasia of the boy may be associated with the stimulation of increased estrogen. The hyperplasia of the pituitary gland may lead to the decline of FT4 in the patient, and the symptoms of language development delay appear.

The chicken essence seasoning taken in by the patient was analyzed by HPLC-MS, and a kind of phytosterol was detected. Chicken essence seasoning is a compound seasoning commonly used in Chinese cooking to bolster flavors. It is processed based on monosodium glutamate by adding edible salt, chicken, chicken bone, flavored disodium nucleotide, and other accessories, and it has the flavor of chicken. Phytosterol is often used as a chicken feed additive (approved by the Ministry of Agriculture of China in 2008) to improve animal protein synthesis, promote animal growth, and lessen the content of cholesterol in eggs and meat. Therefore, phytosterol residues in chicken essence seasoning may result from the chicken fed with phytosterol.

As a steroid compound, phytosterol has a similar chemical structure to steroids, which is a precursor of steroid hormone synthesis and shows certain hormone activity in the body [8]. Some animal research findings indicate that phytosterols produce an increase in circulating testosterone concentration in males [9] or are related to precursor chemicals of testosterone [10]. In addition, phytosterols can be converted to testosterone by microorganisms [11]. These studies show that phytosterols may lead to increased testosterone levels in the body. Furthermore, several research studies have revealed that phytosterols have estrogen-like effects. The β-sitosterol and the soysterol extracts, which are typical phytosterols, had estrogenic effects on MCF-7 cell growth in vitro and induced cell proliferation [12]. Petteri Nieminen and others [13] used 50 mg/kg/day phytosterols to intervene for 2 weeks in the European Polecat; the results showed an increase in the plasma estradiol. In the study by Petteri Nieminen et al. [14] on the effects of phytosterols on endocrinology and metabolism in the field voles, the results showed that the plasma estradiol and testosterone concentrations of males were higher due to phytosterol supplement at 5 mg/kg/day. In a human trial [15], 11 adult female subjects ingested 8.6 g of phytosterols daily for 28 days, with no significant effect on serum estrogen levels, but there was no comparison of male sex hormone levels. The case we report is a 20-month-old boy, which is quite different from the subjects in the human trial described above. Considering that children are extremely sensitive to any alteration of their hormonal environment [16^, 17], and in combination with the findings of animal research, it is highly reasonable to suspect that the high testosterone and estradiol levels in the patient are related to the long-term intake of phytosterols, which in turn led to the development of penis and pubic hair as well as breast development in this boy.

In recent years, some cases of premature development in children caused by percutaneous exposure to androgen-containing preparations [18^-21], lavender products [22^, 23], and endocrine-disrupting chemicals such as pesticides [24] have been reported, but precocious puberty directly caused by a daily diet flavoring is relatively rare. As a flavoring, chicken essence seasoning is only used to improve food flavor and should be added properly. Moreover, the work of the liver and kidneys of children is not yet fully developed, and the additives and sodium salts in the seasoning will cause a burden to the liver and kidneys, so they should have less or not. This case had a long-term and excessive consumption of chicken essence seasoning, which led to the accumulation of phytosterols in the body and in turn triggered a series of early development symptoms and even affected liver function.

For one thing, this report shows the importance of lifestyle for the pubertal development in children. To explore the reasons for children’s precocious puberty (especially for young patients) when pathological causes are excluded, we should pay more attention to the patient’s lifestyle and consider exogenous substances that may cause these symptoms. For another, more attention should be paid to the effect of phytosterols on the growth and development of children. The effects of phytosterols on individual endocrine and metabolism differ depending on the type of phytosterol, dose, duration of exposure, species, and developmental stage of the individual. More research on phytosterols’ sex hormone-like effects and mechanism in humans (particularly in prepubertal children) is needed. This case report provided an essential research direction.

Acknowledgments

We thank the patient and his family members for their support and participation.

Statement of Ethics

Ethical approval of the Local Review Board was not required for this study in accordance with local guidelines. Written informed consent was obtained from the patient’s parents for the publication of any data and images included in this article.

Conflict of Interest Statement

The authors have nothing to disclose.

Funding Sources

This study was supported by the Natural Science Foundation of China (81872637, 81903341, 82173534), Shanghai Professional and Technical Services Platform (18DZ2294100), Key Subject Program for Clinical Nutrition from the Shanghai Municipal Health Commission (2019ZB0103), and Key discipline construction project of the 3-year action Plan of Shanghai Public Health System (GWV-10.1-XK07).

Author Contributions

Shijian Liu and Xiumin Wang performed study design and supervision. Peng Xue, Yirou Wang, and Yao Chen drafted the manuscript. Peng Xue, Yirou Wang, Xiaoyu Wu, Yao Chen, Yijun Tang, and Yu Ding collected and analyzed the data. Peng Xue, Yirou Wang, Yao Chen, Xiumin Wang, and Shijian Liu performed data interpretation. Shijian Liu and Xiumin Wang critically reviewed and revised the manuscript.

Data Availability Statement

All data analyzed during this study are included in this article. Further inquiries can be directed to the corresponding author.