Combined Pituitary Hormone Deficiency (CPHD)

Combined Pituitary Hormone Deficiency (CPHD), or Multiple Pituitary Hormone Deficiency (MPHD), is defined as the underproduction of two or more anterior pituitary hormones, including growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), gonadotropins (LH/FSH), and prolactin.
Genetic Forms: Mutations in genes encoding sequentially expressed transcription factors responsible for pituitary ontogeny are a primary cause.
- PROP1: The most common genetic cause of CPHD. It causes deficiencies in GH, TSH, prolactin, gonadotropins, and frequently a progressive, later-onset deficiency of ACTH.
- POU1F1 (PIT1): Causes deficiencies limited to GH, prolactin, and TSH.
- LHX3: Associated with CPHD, sensorineural deafness, and a short, rigid cervical spine with limited neck rotation.
- HESX1: Associated with variable pituitary deficiencies and Septo-optic dysplasia (optic nerve hypoplasia, absence of septum pellucidum).
Acquired and Developmental Forms: CPHD can result from congenital brain malformations (holoprosencephaly, anencephaly), central nervous system tumors (craniopharyngiomas, germinomas), cranial irradiation, traumatic brain injury, or infiltrative diseases like Langerhans cell histiocytosis.

Neonates with congenital CPHD frequently present with life-threatening emergencies, including severe hypoglycemia (due to GH and ACTH deficiency), prolonged conjugated and unconjugated cholestatic jaundice, and micropenis with or without cryptorchidism in males.
Children classically exhibit severe postnatal growth failure, immature facies, truncal adiposity, and delayed skeletal maturation.
During adolescence, patients typically present with delayed or absent puberty due to concurrent hypogonadotropic hypogonadism.

Hormonal Profiling: Requires baseline and dynamic stimulation testing to confirm deficiencies of GH (e.g., failed GH provocation), cortisol (failed ACTH stimulation), TSH (low free T4 with inappropriately low/normal TSH), and gonadotropins.
Neuroimaging: Magnetic Resonance Imaging (MRI) is the modality of choice. Many cases demonstrate a classic anatomic triad: a hypoplastic anterior pituitary gland, an attenuated or absent pituitary stalk, and an ectopic posterior pituitary bright spot.

Therapy involves lifelong physiological replacement of the deficient hormones.
If both ACTH and TSH are deficient, glucocorticoid replacement (hydrocortisone) must absolutely be initiated before thyroid hormone (levothyroxine) replacement; administering thyroxine first accelerates cortisol clearance and can precipitate a fatal acute adrenal crisis.
Increased "stress dosing" of hydrocortisone is mandatory during periods of febrile illness, trauma, or surgery.
Therapy also includes recombinant human GH to achieve normal adult height and sex steroids at an appropriate age to induce puberty.