Sex hormone-binding globulin (SHBG) or sex steroid-binding globulin (SSBG) is a glycoprotein that binds to androgens and estrogens. When produced by the Sertoli cells in the seminiferous tubules of the testis, it is called androgen-binding protein (ABP).
Function
Testosterone and estradiol circulate in the bloodstream, loosely bound mostly to serum albumin (~54%), and to a lesser extent bound tightly to SHBG (~44%). Only a very small fraction of about 1 to 2% is unbound, or "free," and this biologically active and able to enter a cell and activate its receptor. SHBG inhibits the function of these hormones. Thus, the local bioavailability of sex hormones is influenced by the level of SHBG. Because SHBG binds to testosterone (T) and dihydrotestosterone (DHT), these hormones are made less lipophilic and become concentrated within the luminal fluid of the seminiferous tubules. The higher levels of these hormones enable spermatogenesis in the seminiferous tubules and sperm maturation in the epididymis. SHBG's production is regulated under the influence of FSH on Sertoli cells, enhanced by insulin, retinol, and testosterone.
The relative binding affinity of various sex steroids for SHBG is dihydrotestosterone (DHT) > testosterone > androstenediol > estradiol > estrone. DHT binds to SHBG with about 5 times the affinity of testosterone and about 20 times the affinity of estradiol. Estrone sulfate and estriol are also poorly bound by SHBG. Less than 1% of progesterone is bound to SHBG.
SHBG levels are usually about twice as high in women as in men.
Biochemistry
Biosynthesis
SHBG is produced mostly by the liver and is released into the bloodstream. Other sites that produce SHBG include the brain, uterus, testes, and placenta. Overlapping on the complementary DNA strand is the gene for spermidine/spermine N1-acetyltransferase family member 2 (SAT2). Nearby are the genes for p53 and ATP1B2, and fragile X mental retardation, autosomal homolog 2 (FXR2) on the complementary strand. There are eight exons, of which exon 1 has three variations called 1L, 1T and 1N which are triggered by three promoters: P<sub>L</sub>, P<sub>T</sub> and P<sub>N</sub> respectively. SHBG comes with the 1L, 2, 3, 4, 5, 6, 7, and 8 exons connected together. A variation includes SHBG-T which is missing exon 7 but with exon 1T promoted by promoter P<sub>T</sub> on the opposite strand, which shared with that for SAT2.
Polymorphisms
There are variations in the genetic material for this protein that have different effects.
In humans common polymorphisms include the following:
Rs6259, also called Asp327Asn location 7633209 on chromosome 17, results in there being an extra N-glycosylation site, and so an extra sugar can be attached. This results in a longer circulation half-life for the protein, and raised levels. Health effects include a lowered risk of endometrial cancer and an increased risk of systemic lupus erythematosus.
Rs6258 also called Ser156Pro is at position 7631360 on chromosome 17.
Rs727428 position 7634474 is in several percent of humans.
(TAAAA)(n) is five base pairs that repeats a variable number of times on the opposite DNA strand.
Promoter activation
The mechanism of activating the promoter for SHBG in the liver involves hepatocyte nuclear factor 4 alpha (HNF4A) binding to a DR1-like cis-element which then stimulates production. Competing with HNF4A at a third site on the promoter is PPARG-2 which reduces copying the gene to RNA. If the HNF4A level is low, then COUP-TF binds to the first site and turns off production of SHBG.
SHBG has two laminin G-like domains which form pockets that bind hydrophobic molecules. The steroids are bound by the LG domain at the amino end of the protein.
Metals
A calcium ion is needed to link the two elements of the dimer together. Also a zinc ion is used to orient an otherwise disorganised part of the peptide chain. was downregulation of hepatocyte nuclear factor 4 (HNF4).
Blood values
Reference ranges for blood tests for SHBG have been developed:
{|class="wikitable"
! Population !! Range
|-
| Adult female, premenopausal || 40–120 nmol/L
|-
| Adult female, postmenopausal || 28–112 nmol/L
|-
| Adult male || 20–60 nmol/L
|-
| Infant (1–23 months) || 60–252 nmol/L
|-
| Prepubertal (2–8 years) || 72–220 nmol/L
|-
| Pubertal female || 36–125 nmol/L
|-
| Pubertal male || 16–100 nmol/L
|}
Clinical significance
High or low levels
thumb|right|400px|class=skin-invert-image|Levels of sex hormones and SHBG during pregnancy in women.
thumb|right|400px|class=skin-invert-image|Levels of SHBG and estradiol during pregnancy in women. For SHBG the lines are the mean and 95th percentile levels while the points are individual measurements.
SHBG levels are <em>decreased</em> by androgens, administration of anabolic steroids, polycystic ovary syndrome (PCOS), hypothyroidism, obesity, Cushing's syndrome, and acromegaly. Low SHBG levels increase the probability of type 2 diabetes. SHBG levels <em>increase</em> with estrogenic states (oral contraceptives), pregnancy, hyperthyroidism, cirrhosis, anorexia nervosa, and certain drugs. Long-term calorie restriction increases SHBG in rodents and men, while lowering free and total testosterone and estradiol and having no effect on DHEA-S, which lacks affinity for SHBG. PCOS is associated with insulin resistance and excess insulin lowers SHBG, which increases free testosterone levels.
In utero, the human fetus has a low level of SHBG, allowing increased activity of sex hormones. After birth, the SHBG level rises and remains at a high level throughout childhood. At puberty the SHBG level halves in girls and goes down to a quarter in boys. Such effects apparently involve direct action at the cellular level where it became apparent that cell membranes of certain tissues contain specific high-affinity SHBG receptors.
Coagulation
SHBG is a useful correlate and indirect marker of estrogen-induced procoagulation and by extension thrombosis, for instance with birth control pills.
Medications
Oral contraceptives containing ethinylestradiol can increase SHBG levels 2- to 4-fold and decrease free testosterone concentrations by 40 to 80% in women. They can be used to treat symptoms of hyperandrogenism like acne and hirsutism.
Some medications, such as certain anabolic steroids like mesterolone and danazol and certain progestins like levonorgestrel and norethisterone, have high affinity for SHBG and can bind to it and displace endogenous steroids from it, thereby increasing free concentrations of these endogenous steroids. It has been estimated that therapeutic levels of danazol, methyltestosterone, fluoxymesterone, levonorgestrel, and norethisterone would respectively occupy or displace from testosterone 83–97%, 48–69%, 42–64%, 16–47%, and 4–39% of SHBG binding sites, while others with low affinity for SHBG such as ethinylestradiol, cyproterone acetate, and medroxyprogesterone acetate would occupy or displace from testosterone 1% or fewer SHBG binding sites.
Selective androgen receptor modulators (SARMs) also reduce SHBG.
{| class="wikitable center sortable mw-collapsible mw-collapsed" style="width:675px; text-align:left; margin-left:auto; margin-right:auto; border:none;"
|+ class="nowrap" | Affinities of 70 medications for SHBG and CBG
|-
! Compound || Structure || data-sort-type="number" | SHBG<br /> (%) || data-sort-type="number" | SHBG<br />K (10<sup>6</sup> M<sup>−1</sup>) || data-sort-type="number" | CBG<br /> (%) || data-sort-type="number" | CBG<br />K (10<sup>6</sup> M<sup>−1</sup>)
|-
| Aminoglutethimide || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Androstanolone || Steroidal || 220 || 5500 || 1.3 || 0.83
|-
| Betamethasone || Steroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Cholecalciferol || Steroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Cimetidine || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Clomifene || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Cortisol (hydrocortisone) || Steroidal || 0.13 || 1.6 || 100 || 76
|-
| Cortisone acetate || Steroidal || 0.10 || 1.2 || <0.1 || <0.1
|-
| Cyproterone acetate || Steroidal || 0.10 || 1.2 || <0.1 || <0.1
|-
| Danazol || Steroidal || 18 || 240 || 10 || 6.5
|-
| Dexamethasone || Steroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Diazoxide || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Diethylstilbestrol || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Digitoxin || Steroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Digoxin || Steroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| -DOPA || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Dopamine || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Enclomiphene || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Epinephrine || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Estradiol || Steroidal || 49 || 680 || <0.1 || <0.1
|-
| Estradiol benzoate || Steroidal || 0.70 || 8.6 || <0.1 || <0.1
|-
| Ethinylestradiol || Steroidal || 0.80 || 9.9 || <0.1 || <0.1
|-
| Ethisterone || Steroidal || 55 || 780 || 0.33 || 0.21
|-
| Fludrocortisone || Steroidal || <0.01 || <0.2 || 0.74 || 0.47
|-
| Fluoxymesterone || Steroidal || 4.8 || 60 || <0.1 || <0.1
|-
| Flutamide || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Homovanillic acid || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Hydrocortisone hemisuccinate || Steroidal || <0.01 || <0.2 || 8.7 || 5.6
|-
| Indometacin || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Levonorgestrel || Steroidal || 31 || 420 || <0.1 || <0.1
|-
| Medroxyprogesterone || Steroidal || 0.15 || 1.9 || 13 || 8.1
|-
| Medroxyprogesterone acetate || Steroidal || 0.08 || 1.0 || 6.5 || 4.2
|-
| Melatonin || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Mesterolone || Steroidal || 180 || 3600 || <0.1 || <0.1
|-
| Mestranol || Steroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Methoxytryptophol || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Methyldopa || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Methylserotonin || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Methyltestosterone || Steroidal || 39 || 530 || <0.1 || <0.1
|-
| Metiamide || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Metribolone || Steroidal || 1.7 || 21 || 0.36 || 0.23
|-
| Metyrapone || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Mexrenone || Steroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Nafoxidine || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Nandrolone || Steroidal || 5.8 || 72 || 0.10 || 0.63
|-
| Norepinephrine || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Norethisterone || Steroidal || 11 || 140 || 0.28 || 0.18
|-
| Noretynodrel || Steroidal || 1.3 || 16 || 0.16 || 0.10
|-
| Normetanephrine || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Phenytoin || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Potassium canrenoate || Steroidal || 0.18 || 2.2 || 0.83 || 0.53
|-
| Prednisolone || Steroidal || 0.04 || 0.49 || 59 || 41
|-
| Prednisone || Steroidal || 0.17 || 2.1 || 5.0 || 3.2
|-
| Progesterone || Steroidal || 0.71 || 8.8 || 36 || 24
|-
| Promegestone || Steroidal || 0.007 || 0.09 || 0.40 || 0.25
|-
| Prorenone || Steroidal || 8.2 || 100 || <0.1 || <0.1
|-
| Reserpine || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Rifampin || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Serotonin || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Spironolactone || Steroidal || 0.03 || 0.37 || <0.1 || <0.1
|-
| Tamoxifen || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Testolactone || Steroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Testosterone || Steroidal || 100 || 1600 || 8.3 || 5.3
|-
| Testosterone enanthate || Steroidal || 0.007 || 0.086 || <0.1 || <0.1
|-
| data-sort-value="Thioprogesterone, 7α-" | 7α-Thioprogesterone || Steroidal || 0.06 || 0.74 || 36 || 24
|-
| data-sort-value="Thiospironolactone, 7α-" | 7α-Thiospironolactone || Steroidal || 0.59 || 7.3 || <0.1 || <0.1
|-
| Thyroxine || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Triiodothyronine || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Trimethyltrienolone || Steroidal || 0.90 || 11 || 0.11 || 0.07
|-
| Vanillylmandelic acid || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|-
| Zuclomifene || Nonsteroidal || <0.01 || <0.2 || <0.1 || <0.1
|- class="sortbottom"
| colspan="6" style="width: 1px;" | The reference ligands (100%) for the (%) values were testosterone for SHBG and cortisol for .
|}
{| class="wikitable center sortable mw-collapsible mw-collapsed" style="width:425px; text-align:left; margin-left:auto; margin-right:auto; border:none;"
|+ class="nowrap" | Affinities of 21 progestins for SHBG and CBG
|-
! Progestogen || data-sort-type="number" | SHBG (%) || data-sort-type="number" | CBG (%)
|-
| 17α-Allyl-19-nortestosterone || <1 || ?
|-
| Allylestrenol || <1 || ?
|-
| Chlormadinone acetate || <1 || <1
|-
| Cyproterone acetate || <1 || <1
|-
| Desogestrel || <1 || <1
|-
| Dienogest || <1 || <1
|-
| Drospirenone || <1 || <1
|-
| Etonogestrel || 15 || <1
|-
| Gestodene || 40 || <1
|-
| Levonorgestrel || 50 || <1
|-
| Medroxyprogesterone acetate || <1 || <1
|-
| Megestrol acetate || <1 || <1
|-
| Nomegestrol acetate || <1 || <1
|-
| Norelgestromin || <1 || ?
|-
| Norethisterone || 16 || <1
|-
| Noretynodrel || <1 || <1
|-
| Norgestimate || <1 || <1
|-
| Progesterone || <1 || 36
|-
| Promegestone || <1 || <1
|-
| Segesterone acetate || <1 || ?
|-
| Δ<sup>4</sup>-Tibolone || 1 || <1
|- class="sortbottom"
| colspan="3" style="width: 1px;" | Values are (%). The reference ligand (100%) for SHBG was dihydrotestosterone and for was cortisol.
|}
{| class="wikitable center sortable mw-collapsible mw-collapsed" style="width:300px; text-align:left; margin-left:auto; margin-right:auto; border:none;"
|+ class="nowrap" | Affinities of 14 for SHBG
|-
! Compound || data-sort-type="number" | SHBG (%)
|-
| 5α-Androstane-3β,17β-diol || 17
|-
| 5β-Androstane-3α,17β-diol || 5
|-
| Dihydrotestosterone || 100
|-
| Ethylestrenol || <1
|-
| Fluoxymesterone || <1
|-
| Mesterolone || 440
|-
| Metandienone || 2
|-
| Metenolone || 3
|-
| Methyltestosterone || 5
|-
| Metribolone || <1
|-
| Nandrolone || 1
|-
| Oxymetholone || <1
|-
| Stanozolol || 1
|-
| Testosterone || 19
|- class="sortbottom"
| colspan="2" style="width: 1px;" | Values are (%). The reference ligand (100%) for SHBG was dihydrotestosterone.
|}
{| class="wikitable center sortable mw-collapsible mw-collapsed" style="width:300px; text-align:left; margin-left:auto; margin-right:auto; border:none;"
|+ class="nowrap" | Affinities of 41 steroids for SHBG
|-
! Compound !! data-sort-type="number" | SHBG (%)
|-
| 3β-Androstanediol || 100
|-
| Androstenediol || 77
|-
| Bolandiol || 24
|-
| Dihydroethisterone || 100
|-
| Dihydroethyltestosterone|| 18–21<!--Source reported both 18 and 21 for the same structure in different tables-->
|-
| Dihydromethylandrostenediol|| 77
|-
| Dihydronandrolone || 44
|-
| Dihydrotestosterone || 100
|-
| Dihydrotrestolone|| 47
|-
| 4,17α-Dimethyltestosterone|| 97
|-
| Drostanolone || 39
|-
| Ethisterone || 92
|-
| Fluoxymesterone || 3
|-
| 11-Ketodihydrotestosterone || 0
|-
| Medroxyprogesterone acetate || 16
|-
| Megestrol acetate || 0
|-
| Mestanolone || 84
|-
| Methasterone || 58
|-
| Methyl-1-testosterone || 69
|-
| Methylandrostenediol || 40
|-
| Methyltestosterone || 64
|-
| Mibolerone || 6
|-
| Nandrolone || 16
|-
| Nandrolone decanoate || 0
|-
| Nandrolone phenylpropionate || 0
|-
| Norethandrolone || 3
|-
| Norethisterone || 21
|-
| Normethandrone || 7
|-
| Oxandrolone || 0
|-
| Oxymetholone || 3
|-
| Progesterone || 13
|-
| Stanozolol || 36
|-
| 1-Testosterone || 98
|-
| Testosterone || 82
|-
| Testosterone benzoate || 8
|-
| Testosterone cypionate || 6
|-
| Testosterone enanthate || 9
|-
| Δ<sup>4</sup>-Tibolone || 8
|-
| Trestolone || 12
|-
| Trestolone enanthate || 12
|-
| Vinyltestosterone || 36
|- class="sortbottom"
| colspan="2" style="width: 1px;" | Values are (%). The reference ligand (100%) for SHBG was dihydrotestosterone.
|}
{| class="wikitable center sortable mw-collapsible mw-collapsed" style="width:300px; text-align:left; margin-left:auto; margin-right:auto; border:none;"
|+ class="nowrap" | Affinities of 11 steroids for SHBG and CBG
|-
! Compound || (%) || (%)
|-
| Aldosterone || <0.2 || 6.0
|-
| Corticosterone || <0.2 || 107
|-
| Cortisol || <0.2 || 100
|-
| Dexamethasone || <0.2 || <0.1
|-
| Dihydrotestosterone || 100 || 0.8
|-
| Estradiol || 8.7 || <0.1
|-
| Metribolone || 0.2 || <0.1
|-
| Moxestrol || <0.2 || <0.1
|-
| Progesterone || <0.2 || 25
|-
| Promegestone || <0.2 || 0.9
|-
| Testosterone || 26 || 3
|- class="sortbottom"
| colspan="9" style="width: 1px;" | Values are (%). The reference ligand (100%) for SHBG was dihydrotestosterone and for was cortisol.
|}
{| class="wikitable sortable mw-collapsible mw-collapsed" style="width:500px; text-align:left; margin-left:auto; margin-right:auto; border:none;"
|+ class="nowrap" | Affinities of 9 estrogens for SHBG
|-
! Compound !! data-sort-type="number" | to<br /> (%) !! data-sort-type="number" | Bound to<br /> (%) !! data-sort-type="number" | Bound to<br />albumin (%)
|-
| 17β-Estradiol || 50 || 37 || 61
|-
| Estrone || 12 || 16 || 80
|-
| Estriol || 0.3 || 1 || 91
|-
| Estrone sulfate || 0 || 0 || 99
|-
| 17β-Dihydroequilin || 30 || ? || ?
|-
| Equilin || 8 || 26 || 13
|-
| 17β-Dihydroequilin sulfate || 0 || ? || ?
|-
| Equilin sulfate || 0 || ? || ?
|-
| Δ<sup>8</sup>-Estrone || ? || ? || ?
|- class="sortbottom"
| colspan="4" style="width: 1px;" | The reference ligand (100%) for the SHBG (%) values was testosterone.
|}
Endogenous steroids
Measurement
When checking serum estradiol or testosterone, a total level that includes free and bound fractions can be assayed, or the free portion may be measured alone. Sex hormone-binding globulin can be measured separately from the total fraction of testosterone.
A free androgen index expresses the ratio of testosterone to SHBG and can be used to summarize the activity of free testosterone.
Affinity and binding
{| class="wikitable center sortable mw-collapsible mw-collapsed" style="width:100%; text-align:left; margin-left:auto; margin-right:auto; border:none;"
|+ class="nowrap" |
|-
! rowspan="2" | Steroid !! colspan="2" | SHBG affinity !! colspan="5" | Plasma protein binding in men !! colspan="5" | Plasma protein binding in women (follicular phase)
|-
! (%) !! K (10<sup>6</sup> M<sup>−1</sup>) !! Total (nM) !! Unbound (%) !! SHBG (%) !! CBG (%) !! Albumin (%) !! Total (nM) !! Unbound (%) !! SHBG (%) !! CBG (%) !! Albumin (%)
|-
| Aldosterone || 0.017 || 0.21 || 0.35 || 37.1 || 0.10 || 21.2 || 41.6 || 0.24 || 36.8 || 0.23 || 21.9 || 41.2
|-
| data-sort-value="Androstanediol, 3α-" | 3α-Androstanediol || 82 || 1300 || 0.41 || 0.85 || 13.7 || data-sort-value="0" | <0.1 || 85.5 || 0.068 || 0.71 || 27.9 || data-sort-value="0" | <0.1 || 71.4
|-
| Androstenediol || 97 || 1500 || 4.3 || 3.24 || 60.4 || data-sort-value="0" | <0.1 || 36.3 || 2.4 || 1.73 || 78.8 || data-sort-value="0" | <0.1 || 19.4
|-
| Androstenedione || 2.3 || 29 || 4.1 || 7.85 || 2.82 || 1.37 || 88.0 || 5.4 || 7.54 || 6.63 || 1.37 || 84.5
|-
| Androsterone || 1.1 || 14 || 2.0 || 4.22 || 0.73 || 0.52 || 94.5 || 1.5 || 4.18 || 1.77 || 0.54 || 93.5
|-
| Corticosterone || 0.18 || 2.2 || 12 || 3.39 || 0.09 || 77.5 || 19.0 || 7.0 || 3.28 || 0.22 || 78.1 || 18.4
|-
| Cortisol || 0.13 || 1.6 || 400 || 3.91 || 0.08 || 89.5 || 6.57 || 400 || 3.77 || 0.18 || 89.7 || 6.33
|-
| Cortisone || 0.22 || 2.7 || 72 || 16.2 || 0.54 || 38.0 || 45.3 || 54 || 15.8 || 1.30 || 38.6 || 44.3
|-
| Dehydroepiandrosterone || 5.3 || 66 || 24 || 4.13 || 3.38 || data-sort-value="0" | <0.1 || 92.4 || 17 || 3.93 || 7.88 || data-sort-value="0" | <0.1 || 88.1
|-
| data-sort-value="Deoxycorticosterone, 11-" | 11-Deoxycorticosterone || 1.9 || 24 || 0.20 || 2.69 || 0.80 || 36.4 || 60.1 || 0.12 || 2.62 || 1.91 || 36.9 || 58.6
|-
| data-sort-value="Deoxycortisol, 11-" | 11-Deoxycortisol || 1.3 || 16 || 1.4 || 3.37 || 0.67 || 77.1 || 18.9 || 0.60 || 3.24 || 1.57 || 77.1 || 18.1
|-
| Dihydrotestosterone || 220 || 5500 || 1.7 || 0.88 || 59.7 || 0.22 || 39.2 || 0.65 || 0.47 || 78.4 || 0.12 || 21.0
|-
| Estradiol || 49 || 680 || 0.084 || 2.32 || 19.6 || data-sort-value="0" | <0.1 || 78.0 || 0.29 || 1.81 || 37.3 || data-sort-value="0" | <0.1 || 60.8
|-
| Estriol || 0.35 || 4.3 || 0.037 || 8.15 || 0.44 || data-sort-value="0" | <0.2 || 91.3 || 0.10 || 8.10 || 1.06 || data-sort-value="0" | <0.2 || 90.7
|-
| Estrone || 12 || 150 || 0.081 || 3.96 || 7.37 || data-sort-value="0" | <0.1 || 88.6 || 0.23 || 3.58 || 16.3 || data-sort-value="0" | <0.1 || 80.1
|-
| Etiocholanolone || 0.11 || 1.4 || 1.3 || 8.15 || 0.14 || 0.44 || 91.3 || 1.2 || 8.13 || 0.35 || 0.46 || 91.1
|-
| Pregnenolone || 1.1 || 14 || 2.4 || 2.87 || 0.50 || 0.16 || 96.5 || 2.2 || 2.85 || 1.21 || 0.16 || 95.8
|-
| data-sort-value="Pregnenolone, 17α-Hydroxy" | 17α-Hydroxypregnenolone || 0.19 || 2.3 || 5.4 || 4.27 || 0.12 || data-sort-value="0" | <0.1 || 95.5 || 3.5 || 4.26 || 0.30 || data-sort-value="0" | <0.1 || 95.4
|-
| Progesterone || 0.71 || 8.8 || 0.57 || 2.39 || 0.26 || 17.2 || 80.1 || 0.65 || 2.36 || 0.63 || 17.7 || 79.3
|-
| data-sort-value="Progesterone, 17α-Hydroxy" | 17α-Hydroxyprogesterone || 0.8 || 9.9 || 5.4 || 2.50 || 0.31 || 41.3 || 55.9 || 1.8 || 2.44 || 0.73 || 42.1 || 54.7
|-
| Testosterone || 100 || 1600 || 23 || 2.23 || 44.3 || 3.56 || 49.9 || 1.3 || 1.36 || 66.0 || 2.26 || 30.4
|- class="sortbottom"
| colspan="13" style="width: 1px;" | In men, the concentrations of SHBG, CBG, and albumin were 28 nM, 0.7 μM, and 0.56 mM, respectively. In women, the concentrations of SHBG, CBG, and albumin were 37 nM, 0.7 μM, and 0.56 mM, respectively.
|}
Synonyms
SHBG has been known under a variety of different names including:
- Sex hormone-binding globulin (SHBG)
- Sex steroid-binding globulin (SSBG, SBG)
- Sex steroid-binding protein (SBP, SSBP)
- Androgen-binding protein (ABP)
- Estradiol-binding-protein (EBP)
- Testosterone–estradiol binding globulin (TeBG, TEBG)