Kallmann syndrome (KS) is a genetic disorder that prevents a person from starting or fully completing puberty. If left untreated people with Kallmann syndrome will have poorly defined secondary sexual characteristics, show signs of hypogonadism, almost invariably be infertile and be at increased risk of developing osteoporosis. [1]
Kallmann syndrome is a form of a group of conditions termed hypogonadotropic hypogonadism. Kallmann syndrome has an additional symptom of a total lack of sense of smell or a reduced sense of sense of smell which distinguishes it from other forms of hypogonadotropic hypogonadism. [1]
The underlying cause of the condition is a failure in the correct production or activity of the hormone normally produced by the hypothalamus called GnRH. This failure can lead to problems with the normal progression of puberty, failure of the reproductive cycle and hypogonadism. Hypogonadism is characterised by low levels of the sex hormones testosterone in males or oestrogen and progesterone in females. A range of other physical symptoms affecting the face, hands and skeletal system can also occur in some cases of Kallmann syndrome or hypogonadotropic hypogonadism. Diagnosis normally occurs during teenage years when puberty fails to start. Treatment for both males and females is normally required life long. Hormone replacement therapy ( HRT) is the major form of treatment with the aim to replace the missing testosterone or oestrogen / progesterone. Specialised fertility treatments are also available. [2] [3] [4]
A 2011 study of the Finnish population produced an estimated incidence of 1 in 48,000 people overall, with 1 in 30,000 for males and 1 in 125,000 for females. [5] The condition is more commonly diagnosed in males than in females. [6] Kallmann syndrome was first described by name in a paper published in 1944 by Franz Josef Kallmann, a German- American geneticist. [7] [8] The link between anosmia and hypogonadism had already been noted by the Spanish doctor Aureliano Maestre de San Juan in 1856. [9]
It is normally difficult to distinguish a case of KS / HH from a straightforward constitutional delay of puberty. However, if puberty has not started by either age 14 (girls) or 15 (boys) and one or more of the non-reproductie features mentioned belowe is present then a referral to reproductive endocrinologist might be advisable. [10]
The features of Kallmann syndrome (KS) and other forms of hypogonadotropic hypogonadism (HH) can be split into two different categories; "reproductive" and "non reproductive". [3] [11] [4] [12] [2]
The exact genetic nature of each particular case of KS / HH will determine which, if any, of the non-reproductive features will occur. The severity of the symptoms will also vary from case to case. Even family members will not show the same range or severity of symptoms. [2]
KS / HH is most often present from birth but adult onset versions are found in both males and females. The hypothalamic-pituitary-gonadal axis (HPG axis) functions normally at birth and well into adult life giving normal puberty and normal reproductive function. The HPG axis then either fails totally or is reduced to a very low level of GnRH release, in adult life with no obvious cause such as a pituitary tumour. This will lead to a fall in testosterone or oestrogen levels and infertility.
Functional hypothalamic amenorrhoea is seen in females where the HPG axis is suppressed in response to physical or psychological stress or malnutrition. It is reversible with the removal of the stressor.
Some cases of KS / HH appear to reverse during adult life where the HPG axis resumes its normal function and GnRH, LH, and FSH levels return to normal levels. This occurs in an estimated 10 to 20% of cases, primarily normosmic CHH cases rather than KS cases and only found in patients who have undergone some form of testosterone replacement therapy. It is only normally discovered when testicular volume increases while on testosterone treatment alone and testosterone levels return to normal when treatment is stopped. This type of KS/CHH rarely occurs in cases where males have had a history of un-descended testes.
Affected individuals with KS and other forms of HH are almost invariably born with normal sexual differentiation; i.e., they are physically male or female. This is due to the human chorionic gonadotrophin (hCG) produced by placenta at approximately 12 to 20 weeks gestation (pregnancy) which is normally unaffected by having KS or CHH.
People with KS/CHH lack the surge of GnRH, LH, and FSH that normally occurs between birth and six months of age. This surge is particularly important in infant boys as it helps with testicular descent into the scrotum. The surge of GnRH/LH/FSH in non KS/HH children gives detectable levels of testosterone in boys and oestrogen & progesterone in girls. The lack of this surge can sometimes be used as a diagnostic tool if KS/CHH is suspected in a newborn boy, but is not normally distinct enough for diagnosis in girls. [3]
Taken together, it is likely that testosterone has direct effects on bone quality via the androgen receptor as well as indirect effects via conversion to estrogen by aromatase. Bisphosphonates should be first-line therapy in the treatment of male hypogonadism-related osteoporosis, with the consideration for the addition of testosterone replacement therapy.
One possible side effect of having KS/CHH is the increased risk of developing secondary osteoporosis or osteopenia. Oestrogen (females) or testosterone (males) is essential for maintaining bone density.[16] Deficiency in either testosterone or oestrogen can increase the rate of bone resorption while at the same time slowing down the rate of bone formation. Overall this can lead to weakened, fragile bones which have a higher tendency to fracture.
Even a short time with low oestrogen or testosterone, as in cases of delayed diagnosis of KS/CHH can lead to an increased risk of developing osteoporosis but other risk factors are involved so the risk of developing it will vary from person to person.
People with KS/CHH should have a bone density scan at least every five years, even if they are on constant hormone replacement therapy. This interval will be shortened to three years if the patient is already in the at-risk zone (osteopenia) or yearly if the patient has osteoporosis already.
The bone density scan is known as a dual energy X-ray absorptiometry scan (DEXA or DXA scan). It is a very simple straightforward test, taking less than 15 minutes to perform. It involves taking a specialised X-ray picture of the spine and hips and measuring the bone mineral density and comparing the result to the average value for a young healthy adult in the general population.[17]
Adequate calcium levels, and probably more importantly vitamin D levels are essential for healthy bone density. Some patients with KS/CHH will have their levels checked and may be prescribed extra vitamin D tablets or injections to try to prevent the condition getting worse. The role of vitamin D for general overall health is under close scrutiny at the moment with some researchers claiming vitamin D deficiency is prevalent in many populations and can be linked to other disease states.
Some people with severe osteoporosis might be prescribed bisphosphonates to preserve bone mass. Exercise, especially weight bearing and resistance exercise, is known to reduce the risk of osteoporosis.
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In males with KS / CHH infertility is primarily due the lack of sperm production within the testes. Sperm production can be achieved through either the use of GnRH administered via a micro infusion pump or through the use of gonadotropin injections ( hCG, FSH, hMG). The time taken to achieve adequate sperm production for natural conception will vary from person to person. If the pre treatment testes are very small and there has been a history of undescended testes it might take longer to achieve sperm production. In these cases assisted reproductive technology such as sperm retrieval using testicular sperm extraction (TESE) and / or intracytoplasmic sperm injection (ICSI) might be required. [26]
In females with KS / CHH infertility is primarily due to the lack of maturation of eggs located within the ovaries. Ovulation induction can be achieved either with pulsatile GnRH therapy or alternatively with gonadotropin injections ( hCG, FSH, hMG) given at set intervals to trigger the maturation and release of the egg to allow for natural conception. [26]
The gonadotrophin deficiency in men and women with nCHH/KS is a cause of infertility resulting from failed gamete production and/or maturation (5-9). In men with CHH/KS, infertility is due to absent sperm production (5,6,27,28). However, spermatogenesis can be induced in most cases by either long-term pulsatile GnRH administration via a microinfusion pump, or by exogenous gonadotropin injections 5,6,27,28). A number of studies conducted over the past 30 years have clearly demonstrated that these treatments can be effective (5-9,27,28). In the most difficult cases (patients with very small testes and/or with cryptorchidism)(29,30), longer treatment may be required to conceive as well as use of assisted reproductive techniques (ART) i.e. microsurgical testicular sperm extraction (micro-TESE) and/or intracytoplasmic sperm injection (ICSI) (27,28,31,32).
[27] [27] [27] [27] [27] [27] [27]
Abnormalities in various genes have be shown to disrupt the ability of the hypothalamus to produce gonadotrophin releasing hormone GnRH which in turn causes the pituitary to fail to release sufficient levels of follicle-stimulating hormone (FSH) and luteinising hormone (LH). LH and FSH have a direct action on the testes in men and ovaries in women. [12]
Sixteen known gene defects have so far been shown to cause a disruption in GnRH production. [36] These gene defects can be split into two separate groups depending on their resluting action on the hypothalamus.
One group of gene defects disrupt the ability of the hypothalamus itself to produce or release GnRH, leading to a case of HH with an unaffected sense of smell, sometimes called normosmic hypogonadotrophic hypogonadism (nHH). The other major group of gene defects affect the migration of GnRH neurones into the hypothalmus during embryonic development. Since the GnRH neurones and olfactory neurones travel along the same pathways any impairment in GnRH neurone migration also prevents olfactory neurone migration leading to the anosmia or lack of sense of smell seen in Kallmann syndrome.
Table of known genes responsible for cases of Kallmann syndrome and other forms of hypogonadotropic hypogonadism. Listed are the estimated prevalence of cases caused by the specific gene, additional associated symptoms and the form of inheritance. [6] [2] Between 35-45% of cases of KS / CHH have an unknown genetic cause. [25]
Prevalence (%) | OMIM | Name | Gene | Locus | Clinical features | Syndromes Associated | Inheritance pattern |
---|---|---|---|---|---|---|---|
5, [6] 5-10 [2] | 308700 | KAL1 (ANOS1) | KAL1 | Xp22.3 | Anosmia. Bimanual synkinesis. Renal agenesis. | x-linked | |
10 [6] [2] | 147950 | KAL2 | FGFR1 | 8p11.23 | Cleft lip and / or cleft palate. Septo-optic dysplasia. Skeletal anomomalies. Bimanual synkinesis. Hand / foot malformations such as ectrodactyly. Combined pituitary hormone deficiency. | Hartsfield syndrome | Autosomal dominant |
6-16, [6] 5-10 [2] | 146110 | GNRHR | GNRHR | 4q13.2 | Autosomal recessive | ||
6, [6] 5-10 [2] | 612370 | CHD7 | CHD7 | 8q12.2 | Congenital hearing loss. Semicircular canal hypoplasia. | CHARGE syndrome | Autosomal dominant |
3-6, [6] <2 [2] | 610628 | KAL4 | PROK2 | 3p13 | Autosomal recessive | ||
3-6, [6] 5 [2] | 244200 | KAL3 | PROKR2 | 20p12.3 | Combined pituitary hormone deficiency. | Morning Glory syndrome | Autosomal recessive |
3, [6] 2-5 [2] | 615267 | IL17RD | IL17RD | 3p14.3 | Congenital hearing loss. | Autosomal recessive | |
2, [6] 2-5 [2] | 611584 | SOX10 | SOX10 | 22q13.1 | Congenital hearing loss. | Waardenburg syndrome | Autosomal dominant |
2, [6] <2 [2] | 614842 | KISS1 | KiSS-1 | 1q32.1 | Autosomal recessive | ||
2, [6] <2 [2] | 614837 | KISS1R (GPR54) | GPR54 | 19p13.3 | Autosomal recessive | ||
<2 [2] | 612702 | FGF8 | FGF8 | 10q24.32 | Cleft lip and / or cleft palate. Skeletal anomomolies. Bimanual synkinesis. Combined pituitary hormone deficiency. | Autosomal dominant | |
<2, [6] 1 report [2] | 615270 | FGF17 | FGF17 | 8p21.3 | Dandy-Walker syndrome | Autosomal dominant | |
<2 [6] | 164260 | LEP | LEP | 7q32.1 | Early onset of morbid obesity. | Autosomal recessive | |
<2 [6] | 601007 | LEPR | LEPR | 1p31.3 | Early onset of morbid obesity. | Autosomal recessive | |
<2 [6] | 162150 | PCSK1 | PCSK1 | 5q15 | Early onset of morbid obesity. | Autosomal recessive | |
Rare, [6] 1 report [2] | 616030 | FEZF1 | FEZF1 | 7q31.32 | Autosomal recessive | ||
Rare, [6] 1 report [2] | 616031 | CCDC141 | CCDC141 | 2q31.2 | Unknown | ||
Rare, [6] <2 [2] | 614897 | SEMA3A | SEMA3A | 7q21.11 | Autosomal dominant | ||
1 report [2] | 608166 | SEMA3E | SEMA3E | 7q21.11 | CHARGE syndrome | Autosomal dominant | |
Rare [6] | 607961 | SEMA7A | SEMA7A | 15q24.1 | Autosomal dominant | ||
Rare, [6] <2 [2] | 614880 | HS6ST1 | HS6ST1 | 2q14.3 | Cleft lip and / or cleft palate. Skeletal anomalies. | Autosomal dominant | |
Rare, [6] 1 report [2] | 614858 | WDR11 | WDR11 | 10q26.12 | Combined pituitary hormone deficiency. | Autosomal dominant | |
Rare [6] | 614838 | NELF (NSMF) | NELF | 9q34.3 | Autosomal dominant | ||
Rare [6] | 617351 | IGSF10 | IGSF10 | 3q24 | Autosomal dominant | ||
Rare, [6] <2 [2] | 614841 | GNRH1 | GNRH1 | 8p21.2 | Autosomal recessive | ||
Rare, [6] <2 [2] | 614839 | TAC3 | TAC3 | 12q3 | Autosomal recessive | ||
Rare, [6] 5 [2] | 614840 | TACR3 | TACR3 | 4q24 | Autosomal recessive | ||
Rare [6] | 611744 | OTUD4 | OTUD4 | 4q31.21 | Cerebellar ataxia. | Gordon Holmes syndrome | Autosomal recessive |
Rare [6] | 609948 | RNF216 | RNF216 | 7p22.1 | Cerebellar ataxia. | Gordon Holmes syndrome | Autosomal recessive |
Rare [6] | 603197 | PNPLA6 | PNPLA6 | 19p13.2 | Cerebellar ataxia. | Gordon Holmes syndrome | Autosomal recessive |
1 report [2] | 109135 | AXL | AXL | 19q13.2 | Unknown | ||
Rare [6] | 612186 | DMXL2 | DMXL2 | 15q21.2 | Polyendocrine deficiencies and polyneuropathy. | Autosomal recessive | |
Rare [6] | 300473 | NR0B1 (DAX1) | NR0B1 | Xp21.2 | Adrenal hypoplasia. | x-linked | |
1 report [2] | 602748 | DUSP6 | DUSP6 | 12q21.33 | Autosomal dominant | ||
1 report [2] | 614366 | POLR3B | POLR3B | 12q23.3 | Autosomal recessive | ||
1 report [2] | 615266 | SPRY4 | SPRY4 | 5q31.3 | Autosomal dominant | ||
1 report [2] | 615271 | FLRT3 | FLRT3 | 20p12.1 | Autosomal dominant | ||
1 report [2] | 617264 | SRA1 | SRA1 | 19q13.33 | Unknown | ||
Rare [6] | 601802 | HESX1 | HESX1 | 3p14.3 | Septo-optic dysplasia. Combined pituitary hormone deficiency. | Autosomal recessive and dominant |
704 is consensus guidelines
Diagnosis of KS / CHH normal involves a range of clinical, biochemical and radiological tests to exclude other conditions that can cause similar symptoms.
Early treatment in male neonates involves lowering the testes into the correct position in the case of cryptorchidism and treating micropenis if present. There is no early treatment required for female neo
At around the ages of 14 or 15, or earlier if specific additional symptoms such as anosmia are present treatment can be given to both male and
Micropenis: testosterone, DHT or gonadotropin therapy (patients aged 1–6 months) Penile growth Adolescent Patients aged 14–15 years (earlier in the presence of specific signs such as anosmia) Virilization or estrogenization Sexual function Growth and bone health Gonadal maturation and future fertility Psychological wellbeing Male patients: testosterone (oral, injectable or transdermal) Gonadotropins? Genital development Growth and epiphyseal closure Virilization Sexual function Wellbeing Adherence Reversibility Morning serum testosterone levels (trough levels for injections), LH, FSH and inhibin B levels, haemocrit Testosterone treatment will not induce testicular growth or fertility Female patients: estradiol (oral or transdermal) followed by estradiol + progesterone or progestin Breast development Growth and epiphyseal closure Estrogenization Feminized body Menses Sexual function Bone health Wellbeing Adherence Reversibility No specific Estradiol must be increased slowly before the combination of estradiol + progesterone or progestin to maximize breast development and avoid areolar protrusion Adulthood All patients Sexual function Fertility Limiting comorbidities Psychological wellbeing Puberty induction Male patients: Testosterone (injectable or transdermal) hCG ± FSH FSH, FSH + hCG GnRH pump Pubertal development Sexual function and libido Bone health Wellbeing Adherence Fertility Reversibility Tough serum testosterone levels, LH, FSH and inhibin B levels, haematocrit, PSA levels Sex steroid replacement will not induce fertility Female patients: Estradiol (oral or transdermal) Progesterone or progestin FSH + hCG or GnRH pump Pubertal development Sexual function and libido Bone health Wellbeing Adherence Fertility Reversibility Serum levels of estradiol, LH, FSH, inhibin B and AMH
In the 1950s De Morsier and Gauthier reported the partial or complete absence of the olfactory bulb in the brains of men with hypogonadism. [58] [11]
To date at least twenty five different genes have been implicated in causing Kallmann syndrome or other forms of HH through a disruption in the production or activity of GnRH. These genes involved cover all forms of inheritance and no one gene defect has been shown to be common to all cases which makes genetic testing and inheritance prediction difficult. [36] [59]
The number of genes known to cause cases of KS / CHH is still increasing. [12] In addition it is thought that some cases of KS / CHH are caused by two separate gene defects occurring at the same time. [6]
Some of the genes known to be involved in cases of KS / CHH are listed in the Online Mendelian Inheritance in Man (( OMIM)) table at the end of this article.
OMIM | Name | Gene | Locus | Description |
---|---|---|---|---|
308700 | KAL1 | KAL1 (ANOS1) | Xp22.3 | Kallmann syndrome can be inherited as an X-linked recessive trait, in which case there is a defect in the
KAL1 (ANOS1) gene, which maps at chromosome Xp22.3.
[60]
[61]
This genetic form may include synkinesis and renal agenesis. ANOS1 encodes an extracellular matrix glycoprotein, anosmin-1, present in various embryonic tissues including the presumptive olfactory bulbs in the rostral forebrain. The protein is required to promote the embryonic migration of olfactory nerve fibres and GnRH neurons from the olfactory epithelium of the nose into the brain. [62] [63] |
147950 and 612702 | KAL2 | FGFR1 and FGF8 | 8p11.23 and 10q24.32 | Autosomal dominant mutations of FGFR1, encoding fibroblast growth factor receptor 1, or FGF8, encoding one of its ligands (fibroblast growth factor 8), cause about 10% of KS/CHH cases. These genetic forms may include cleft lip and / or palate, hypodontia, hearing impairment, or ectrodactyly (FGFR1 mutations). [64] [65] [66] |
244200 and 610628 | KAL3 | PROKR2 and PROK2 | 20p12.3 and 3p13 | Mutations of PROKR2, encoding prokineticin receptor-2, or PROK2, encoding one of its ligands (prokineticin 2), are involved in autosomal recessive forms of KS (where both alleles of the gene are mutated), but most people carrying mutations in either gene only have one mutated allele, suggesting that they carry at least one additional mutation in another, as yet unidentified in most cases, KS gene (oligogenic forms). [54] |
616030 | FEZF1 | FEZF1 | 7q31.32 | Mutations of FEZF1, encoding a ( zinc finger)-domain containing protein, are involved in an autosomal recessive form of KS. The protein is required for the passage of growing olfactory nerve fibres and GnRH releasing neurones into the brain. [67] |
612370 | CHD7 | CHD7 | 8q12.2 | Mutations of CHD7 have first been reported in CHARGE syndrome, a severe developmental disease affecting multiple organs, which often includes KS. CHD7 encodes a transcriptional regulator that binds to enhancer elements in the nucleoplasm. [21] [68] |
611584 | SOX10 | SOX10 | 22q13.1 | Mutations of SOX10 have first been reported in Waardenburg syndrome, which may include KS in addition to deafness. SOX10 encodes a transcription factor expressed by olfactory ensheathing cells, glial cells of neural crest origin that are permissive for the elongation and targeting of olfactory nerve fibres. [69] |
614897 | SEMA3A | SEMA3A | 7q21.11 | Mutations of SEMA3A, encoding semaphorin 3A (ligand of plexin A1 receptor), involved in the guidance of olfactory nerve fibers into the brain, are thought to be involved in oligogenic forms of KS. [70] |
614838 | NELF | NELF | 9q34.3 | Associated with the migration of the olfactory axons and GnRH neurones during development. |
615271 | FLRT3 | FLRT3 | 20p12.1 | Encodes fibronectin-like domain-containing leucine rich transmembrane protein 3. Protein associated with the function of the KAL2 genes (FGFR1 and FGF8) which allows for the migration of both olfactory axons and GnRH releasing neurones during early embryonic development. [35] |
615270 | FGF17 | FGF17 | 8p21.3 | Encodes fibroblast growth factor 17. Protein associated with the function of the KAL2 genes (FGFR1 and FGF8) which allows for the migration of both olfactory axons and GnRH releasing neurones during early embryonic development. [35] |
615267 | IL17RD | IL17RD | 3p14.3 | Encodes interleukin receptor 17 D. Protein associated with the function of the KAL2 genes (FGFR1 and FGF8) which allows for the migration of both olfactory axons and GnRH releasing neurones during early embryonic development. [35] |
615269 | DUSP6 | DUSP6 | 12q21.33 | Encodes dual specificity phosphate-6. Protein associated with the function of the KAL2 genes (FGFR1 and FGF8) which allows for the migration of both olfactory axons and GnRH releasing neurones during early embryonic development. [35] |
615266 | SPRY4 | SPRY4 | 5q31.3 | Encodes sprouty, Drosphila, homolog of, 4. Protein associated with the function of the KAL2 genes (FGFR1 and FGF8) which allows for the migration of both olfactory axons and GnRH releasing neurones during early embryonic development. [35] |
146110 and 614841 | GNRHR and GNRH1 | GNRHR and GNRH1 | 4q13.2 and 8p21.2 | Biallelic mutations of GNRHR or GNRH1, encoding the GnRH receptor and the hormone GnRH1, respectively, cause normosmic CHH or partial CHH. Binding of GnRH1 to its receptor allows FSH/LH secretion by the pituitary gland. [71] [72] |
614837 and 614842 | KISS1R and KISS1 | KiSS-1 and KiSS-1R | 19p13.3 and 1q32.1 | Biallelic mutations of KISS1R or KISS1, encoding the kisspeptin receptor 1 and the ligand kisspeptin 1, respectively, cause normosmic CHH. Kisspeptin, produced in the hypothalamus, is essential for pulsatile GnRH secretion, and is thought to be involved in the timing of the onset of puberty. [73] [74] |
614840 and 614839 | TACR3 and TAC3 | TACR3 and TAC3 | 4q24 and 12q13.3 | Biallelic mutations of TACR3 or TAC, encoding the receptor of neurokinin B and the ligand neurokinin B, respectively, cause normosmic CHH (usually severe HH with high incidence of micropenis). They are associated with a higher rate of reversible HH than mutations of other CHH genes. Neurokinin B, produced in the hypothalamus, is crucial for GnRH secretion. [75] |
164160 | LEP | LEP | 7q31.2 | Encodes leptin, the ligand of the receptor LEPR. Involved in pulsatile GnRH secretion. |
300200 | DAX1/NROB1 | DAX1 | Xp21.2 | Encodes a nuclear receptor with no known ligand. Known to be a transcription inhibitor. Mutations in DAX1 are thought to cause X-linked recessive forms of CHH in both males and occasionally females. Known to cause pubertal delay in females. |
For both males and females the initial aim for treatment is the development of the secondary sexual characteristics normally seen at puberty. [2] [44] [76] [77] [57] Once this has been achieved continued hormone replacement therapy is required for both males and females to maintain sexual function, bone health, libido and general wellbeing. [3] In males testosterone replacement therapy is required for the maintenance of normal muscle mass. [2]
Early treatment is sometimes required for male infants with suspected KS / CHH to correct un-descended testes and micropenis if present with the use or surgery or gonadotropin or DHT treatment. Females with KS / CHH normally do not require any treatment before the age of adolescence. Currently no treatments exist for the lack of sense of smell, mirror movement of the hands or the absence of one kidney. [3]
Treatment for both males and females with KS / CHH is normally comprised of one of three options [2] [3]
The method and dose of treatment will vary depending on the individual being treated. Initial treatment is normally made with lower doses in younger patients in order to develop the secondary sexual characteristics before adult doses are reached. [2]
For males with KS / CHH the types of testosterone delivery include daily patches, daily gel use, daily capsules, sub cutaneous or intramuscular injections or six monthly implants. Different formulations of testosterone are used to ensure both the anabolic and androgenic effects of testosterone are achieved. [3] [4] Nasal testosterone delivery methods have been developed but their use in KS / CHH treatment has not been formally evaluated. [2]
Gonadotropin therapy in the form of human chorionic gonadotropin (hCG) injections with or without the use of FSH can also be used in male patients to induce secondary sexual characteristic development along with possible fertility induction at the same time. [3]
For females hormone replacement involves the use of oestrogen and progesterone. In females oestrogen only is used first in tablet or gel form in order to maximise breast development before a combination of oestrogen and progesterone is used. [3] [2] Cyclical progesterone is normally required used to help keep the endometrium (lining of the uterus healthy). [2]
In males the monitoring of treatment normally requires the measurement of serum testosterone, inhibin B, haematocrit and prostate-specific antigen (PSA). If injections are used trough levels are taken to ensure an adequate level of testosterone is achieved throughout the injection cycle. [3]
In females monitoring normally comprises of measurement of oestrogen, FSH, LH, inhibin B and anti-Müllerian hormone (AMH). [3]
Standard hormone replacement therapy will not normally induce fertility in either males or females, with no testicular growth in males. Early treatment as adolescents can help with psychological well being of people with KS / CHH. [3]
For males with KS / CHH the types of testosterone delivery include daily patches, daily gel use, daily capsules, sub cutaneous or intramuscular injections or six monthly implants. Different formulations of testosterone are used to ensure both the anabolic and androgenic effects of testosterone are achieved.[3][4]
For females hormone replacement involves the use of oestrogen and progesterone. In females oestrogen only is used first before a combination of oestrogen and progesterone.[3]
For both males and females the initial aim for treatment is the development of the majority of the secondary sexual characteristics normally seen at puberty. Once this has been achieved continued hormone replacement therapy is required for both males and females to maintain sexual function, bone health, libido and general wellbeing.[3]In males testosterone replacement therapy is required for the maintenance of normal muscle mass.[2]
For both males and females standard hormone replacement therapy will not induce fertility or testicular growth in males.[3]
Kallmann syndrome (KS) is a genetic disorder that prevents a person from starting or fully completing puberty. Kallmann syndrome is a form of a group of conditions termed hypogonadotropic hypogonadism. To distinguish it from other forms of hypogonadotropic hypogonadism Kallmann syndrome has the additional symptom of a total lack of sense of smell or a reduced sense of sense of smell. [1] [2] [3]
If left untreated people with Kallmann syndrome will have poorly defined secondary sexual characteristics, show signs of hypogonadism, almost invariably be infertile and be at increased risk of developing osteoporosis. [1] A range of other physical symptoms affecting the face, hands and skeletal system can also occur. [2]
The underlying cause is a failure in the correct production or activity of GnRH hormone by the hypothalamus. This results in low levels of the sex hormones testosterone in males or oestrogen and progesterone in females. Diagnosis normally occurs during teenage years when puberty fails to start. [3]
Treatment for both males and females is normally required life long. Hormone replacement therapy (HRT) is the major form of treatment with the aim to replace the missing testosterone or oestrogen and progesterone. Specialised fertility treatments are also available. [4]
The condition is more commonly diagnosed in males than in females. [6] A 2011 study of the Finnish population produced an estimated incidence of 1 in 48,000 people overall, with 1 in 30,000 for males and 1 in 125,000 for females. [5] Kallmann syndrome was first described by name in a paper published in 1944 by Franz Josef Kallmann, a German- American geneticist. [7] [8] The link between anosmia and hypogonadism had already been noted by the Spanish doctor Aureliano Maestre de San Juan in 1856. [9]
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