Case Presentation

Dr YY Lam

Dept of Paediatrics, KWH

27th Oct, 2005

A patient with an unusual syndrome of adrenal insufficiency

Case History :CKL,M/2yr

FTCS BW 6lbs ,Parents non consanguineousHx of frequent vomiting with solid food

Hx of present illness

Presented with GE and generalised tonic seizure,high fever ,septic shock, intubated and boluses of NS

Status epilepticusD'stix unrecordable low serum glucose 0.4. Sodium 122convulsion poorly controlled despite normal

glucose and NaLorazepam ,phenytoin, midazolam

Cerebral Ischaemia

CT brain(D3) : HIE with cerebral oedema and global ischaemia

GCS remained 3burr hole D6 with ICP monitor, CT brain cerebral

oedem ICP gradually decreased, GCS increased to 5Midazolam was gradually weaned

Sequalae

GCS increased to 7, extubated day 19Spastic quadriplegia, cortical blindness,

maintained on antiepileptic, global delayHospitalised for 14 mths

Suspected adrenal insufficiency

Na lowest 122 mmol/l K 5.4, urea 6.5Hypoglycaemia 0.4, urine ketone 2+Hypotension after high midazolam infusionSuspected adrenal insufficiencyHydrocortisone on day 4 and to oral 20 mg/m2

/day 1 week later

Endocrine investigation

Short synacthen test (30/4)– Cortisol <18(0’), 46(30’),47(60’)– Suboptimal, but ?Affected by dexamethasone

on 28/4 for cerebral edema (0.5mg/kg) Repeated short synacthen test 17/5(off

hydrocortisone 3 days since 14/5)– Cortisol 405(0’),414(30’), 399(60’) – ACTH >275 pmol/l– Renin increased with normal aldosterone

Diagnosis:?CAH

24 hour urine for steroid profile(16-17/5)Significant elevation of tetrahydrocompound

S(THS ), presence of tetrahydroxycorticosterone (THDOC) and 11OH THS

No decrease in cortisol or increased androgen metabolite

Compatible with 11 beta hydroxylase deficiency, ?partial or metabolite suppressed due to hx of treatment

Other endocrine Ix

17 OH progesterone normalTestosterone not increasedDHEAS(28/6) 0.06 umol/l,repeated (8/9) after

prolonged ACTH <0.5Antiadrenal Ab –veVery long chain fatty acid normalUSG adrenal(28/5) no adrenal pathology

Prologed ACTH simulation

Off hydrocortisone, replaced with dexamethasone at physiological dose

IMI synacthen depot 500 mcg daily for 3 days Baseline ACTH 1130,cortisol 91,renin >28ng/ml

and aldosterone 199 pmol/l(n)Post 3rd dose, ACTH 3.7, cortisol 73, 24 hr U

steroid cortisol synthesis blocked, elevated THS, support initial Dx

Progress

Infective, metabolic and toxicology investigations all normal

Brain Bx ischaemic changesBed bound, could not tolerate oral feedingdependent on tube feedingTreated as CAH (partial 11 beta hydroxylase def)

with hydracortisone replacement

11 beta hydroxylase deficiency

Accounts 5 to 8% CAH1/100,000 births ( Morocco Jews,1 in 5000

to 7000)chromosome 8q24.3Also called CYP11B1, regulated by ACTH

Biochemical abnormality

11 deoxycortisol and deoxycorticosterone not efficiently converted to cortisol and corticosterone

-ve inhibition and increased ACTHStimulate zona fasciculata and increased

proximal precursorsDx by increased metabolites in blood or

increased tetrahydrometabolites in 24 hour urineHeterozygous carriers no consistent biochemical

abn even with ACTH stimulation

Clinical feature

Severe classic form

– 2/3 with HT (-ve in our case)– Hypo K occur in minority – Plasma renen usu suppressed and low aldosterone, no

impaired synthesis (renin high in our patient)– Signs of androgen excess or virilization (-ve in our

patient)– Excessive somatic growth, premature closure of

epiphyses,precocious puberty

Treatment

Glucocorticoid replaces cortisol, suppressed ACTH and decreased the excessive androgen production, also controp BP

long standing high BP, antihypertensive Choice: K sparing diuretic+/- Ca channel blockerNot ACEI, unlikely to be effective; not thiazide

diuretic, may cause hypoK

Problems in Mx

Mx as 11 beta hydroxylase deficiency with hydrocortisone

Persistent high ACTH – all >275 despite hydrocortisone for 3 months ( dose

increased gradually from 20 to 30 mg/m2/d)Na low

– Level 127-130, requires Na at 2 mmol/kg/d – High renin despite normal aldosterone, ? insufficiency

Subsequent Progress

Poor oral feedingVideo fluoroscopic swallowing study(6

mths after admission): poor oromotor coordination and accumulation of food in the esophagus and stomach, functional impairment of esophagogastric junction.

contrast swallow ( 8 mths afer admission) confirmed the presence of achalasia

Contrast swallowdilated esophagus,failure of esophagus to relax with contrast hold up , Dx Achalasia

Other anomalies

absent tear production all alongOphthalmologic assessment confirmed cortical

blindness and also documented insufficient tear production.

Schirmer’s test of both eyes was only 0 mm in 5 minutes (normal >10 mm)

Adrenal def, Achalasia, Alacrima : ? Triple A syndrome

Molecular Dx

genomic DNA from the peripheral blood of patient, parents and brother

2 heterozygous mutations detected c.580C>T transition in exon 7, nonsense mutation, also

detected in the mother c.771delG in exon 8,frameshift mutation, also detected in

father and brother patient is a compound heterozygote

Triple A Syndrome

1st reported in 2 pairs of siblings by Allgrove in 1978 (Allgrove syndrome)

alacrima, achalasia, and corticotropin insensitivity AR associated with neurological dysfunction 4A syndrome : autonomic

and other neurologic abnormality Presentation variable in timing and clinical manifestation Mutation AAAS gene MIM*231550

Alacrima

usually the earliest presenting feature, easily overlooked

Schirmer test : decreased tear production is shown by wetting<2mm of a standard test strip in 5 minutes

pathology is either absent or reduced lacrimal glands

Achalasia

Rare in children, incidence 0.1 case/year/100,000 for <14 year

Mayberry, Gut 1988;7:284-287In Triple A syn, Achalasia of the cardia

occurs in about 75% of cases with onset from 0.5 to 16 years

Clark AJL et al, EndocrineReviews 1998;19(6):828-843Can be sole presenting problem and

precedes adrenal disease by 1 to 4 years

Adrenal Insufficiency

Glucocorticoid usu in 1st decade with severe hypoglycaemia, can lead to sudden death

Late presentation in 3rd decade reportedHyperpigmentation commonGlucocorticoid deficiency develops as a

progressive event and adrenal hypoplasia was demonstrated in some by CT scan

mineralocorticoid def up to 15% of patients Grant DB et al Arch Dis Child 1993:68:779-82

adrenal androgen insufficiency rarely reported Dumic M Eur J Pediatr 1991;150: 696-699

Neuropathy

central, peripheral and autonomic neuropathy common

spectrum involvement can be variableCNS:progressive mental retardation, optic

atrophy, clumsiness, ataxia and recurrent seizuresPNS: motorsensory neuropathyANS: around 30% with autonomic dysfunction

e.g. postural hypotension, abnormal cardiovascular reflexes, unequal pupils, abnormal miosis after metacholine eye drops, absent or reduced sweating and impotence

Genetics of Triples A Syndrome

disease locus 12q13, AR Truncating mutations in a novel gene (AAAS)

identified in unrelated patients in 2000 Tullio-Pelet A et al Nature Genet 2000;26(3):332-335

gene encodes a protein of 547 amino acids, ALADIN (alacrima-achalasia-adrenal insufficiency neurologic disorder), WD-repeat family of regulatory proteins

gene widely expressed in endocrine and neuroendocrine derivatives, cerebral structures, and GIT

Genetics

Most reported cases Caucasians1 Japanese patient (2002)1 Chinese girl with achalasia and alacrima

reported in 1994

Pathogenesis

Poorly understood ?neuropathic processesophagus, lower esophageal sphincter and the

lacrimal glands under sympathetic and parasympathetic control

adrenal gland with vagal and splanchnic efferent innervation, ?regulate function of adrenal medulla and cortex

Adrenal denervation in rats leads to impaired growth in adrenal cortex in rats

neonatal sympathectomy leads to impaired glucocorticoid secretion

Pathogenesis

ALADIN localizes to nuclear pore complexes, sole sites of nucleocytoplasmic transport

plays cell type specific role in regulating nucleocytoplasmic transport

role in maintenance and development of tissues Previously postulation of ACTH receptor defect, leading

to adrenocorticotropin insensitivity, but no mutation found in the coding region of ACTH receptor

Abnormal urine steroid metabolite similar to CAH not reported before, ? Significance , need further studies

Outcome of patient CKL

Adrenal insuffiency– hydrocortisone 20mg/m2/d, fludrocortisone 0.2mg daily with salt

supplement Achalasia and malrotation

– OT at 3 yr old: duodenal jejunal junction on the right side of spine and proximal oesophageal dilatation. Malrotation corrected, Heller’s operation for achalasia, with gastrostomy and fundoplication

Alacrima– Artificial tear

Home after 14 months stay, spastic quadriplegia, cortical blindness, ICCC, gastrostomy feeding, also on Anti-epileptic drug

Familial Hypocalciuric Familial Hypocalciuric Hypercalcemia & a Review of Hypercalcemia & a Review of Calcium-Sensing Receptor Calcium-Sensing Receptor DisorderDisorder

Dr. Huen Kwai FunCOS & Con (Paed) TKOH

Case Presentation LCH, F/8 yr , Chinese Referred from SHS because of short stature P1, FTNSD at QEH, BW 5+lbs. No A/N or P/N problems. No consanguinity Breast fed for 2m, then formula fed. +cereal at 9m. Feeding

OK Noted to be short all along. Among shortest in class. No Hx of any chronic diseases , nor drug Px No polyuria, polydipsia, constipation, anorexia, nausea,

vomiting, muscle weakness, abd pain, bone pain nor wt loss Development normal FHx of hypercalcaemia in paternal side

Ht 110.3 cm (4.5 cm<3%); BW 17.6 Kg (3%); BP 119/63 mmHg

P/E – Prepubertal, System exam - nad Father 162.6 cm; Mother 155.1 cm; MPH 152.5 cm (~10%) BA 6.68 yrs at CA 8 yrs FBC, L/RFT, TFT normal Ca 3.00 mmol/L(2.20-2.70), Alb 51 g/L, Corrected Ca 2.88 mmol/L P 1.03 mmol/L(1.1-2.0), ALP 167 (<300 U/L) Mg 0.98 mmol/L (0.69-0.87) 24 hr Urine Ca/Cr clearance ratio <0.01 PTH 9 pg/ml(11-54) at adjusted Ca 2.67 mmol/L

Genetic Study

Mutation for CaSR gene P798T found in 1st, 2nd and 3rd generations

(CW Lam. Clin. Chem. Acta. 2005 Oct 360 (1-2):167-172)

Calcium sensing Extracellular Ca homeostasis Interaction of PTH, calcitonin, vitamin D, calcium on

kidney, bone, gut and parathyroid Ca PTH release Ca 2+ from bone

renal Ca reabsorption production of 1,25 – dihydroxyvitamin D

Calcitonin from C-cells of thyroid gland gut absorption of Ca growth of parathyroid cells transcription of PTH gene

Ca-sensing ability of parathyroid mediated by a receptor on the parathyroid cell surface

extracellular Ca 2+ Phospholipase C activated inositol 1,4,5-triphospate Ca release from intracellular stores

Calcium ion serves as an intracellular second messenger and plays a hormone-like role as an extracellular first messenger

Ca regulates its own handling on the nephrons by at least 2 ways (1) indirectly by altering secretion of PTH (2) directly on the CaSR on kidneys

Biochemical studies suggested Ca-sensing capability of parathyroid cells mediated by a G-protein coupled cell-surface receptor

Calcium-sensing receptor The extracellular calcium-sensing receptor (CaSR) was cloned by Brown

E.M. et al. in 1993 from bovine parathyroid glands

Provided key insights into pathogenesis of inherited human hypo- and hyperCa disorders

A G protein-coupled receptor (GPCR) Consisting 1078 aa residues

Expressed in all tissues related to Ca control (PTH glands, thyroid C-cells, kidneys, intestine and bones)

Also in tissues w no role in maintenance of EC Ca, e.g. brain, skin, and pancreas (Roles ?)

CaSR plays an essential role in regulation

of extracellular Ca homeostasis by

Mediating inhibitory actions of EC calcium on

PTH secretion by parathyroid glands Influencing the rates of renal tubular calcium

reabsorption Secretion of calcitonin by thyroid C-cells

Calcium-sensing receptor3 major domains: A long (~first 612 aa) and hydrophilic aminoterminal EC domain

(ECD) – site of Ca binding, location of most activating and inactivating mutations; dimerization; agonist-binding

A hydrophobic seven-transmembrane domain – involved in signal transduction mechanism from EC domain to respective G protein

A carboxyterminal IC tail (~ last 200 aa)– for cell surface CaSR expression and signal transduction

Schematic representation ofthe principal structural features ofthe predicted HuPCaR4.0 protein.The large amino-terminal domain is locatedextracellularly, and the carboxylterminaldomain is located intracellularly.Symbols are given in the key. SP,predicted signal peptide; HS, hydrophobicsegment. Amino acids that are conservedin all mGluRs and HuPCaR4.0 are shownas filled circles and triangles. The mutationscharacterized in this paper aremarked with X for inactivating mutationsidentified in FHH/NSHPT patients and *for an activating mutation identified in apatient with ADH (J Biol Chem Vol 271,32,19539)

Braz J Med Biol Res 34(5) 2001

Different receptor gene mutations disrupt the receptor’s function in different ways, including

altering its affinity for Ca causing abnormal protein expression and /or

protein folding causing defective communication with G-

proteins and subsequent steps in signaling

Association with genetic human diseasesCaSR-inactivating (loss) mutations – generalized resistance to EC Ca1. Familial hypocalciuric hypercalcemia (FHH) 2. Neonatal severe hyperparathyroidism (NSHPT)

CaSR-activating (gain) mutations – hyperresponsiveness to EC Ca1. Autosomal dominant hypoparathyroidism (ADH)

Familial hypocalciuric hypercalcemia (FHH)

AD w high penetrance > 90%

Majority linkage of ds gene to chromosome 3q (band q21-24). Exception short arm chr 19, band 19p13.3. (Am J Human Genetics,53:193-200)

Inability to find a mutation does not exclude this gene as culprit

Proven by functional studies in human embryonic kidney (HEK 293) cells transfected w CaSRs bearing FHH mutations.

Showed EC50 (The effective conc EC Ca eliciting ½ the max IC Ca

response), i.e. increase in set-point

Both kidneys and parathyroid glands respond abnormally to Ca Exhibit a PTH-independent in renal Ca reabsorption Parathyroid glands shows minimal pathology to mild hyperplasia

Lifelong, mild to moderate but usu asymptomatic hyperCa Inappropriately low urinary Ca excretion (Ca/Cr clearance ratio <

0.01) Hypocalciuria is not PTH dependent Nonsuppressed level of PTH, regardless of hyperCa Normal PTH, Normal ALP, mild increase Mg

No hyperCa-induced morbidity. Urine conc ability, urinary excretion of cAMP, GFR all intact. No

increase risk of nephrocalcinosis nor renal stones

Misdiagnosed primary hyperparathyroidism HyperCa recurred post subtotal parathyroidectomy

Neonatal severe hyperparathyroidism (NSHPT)

Homozygous form of FHH or compound heterozygote

Familial or de novo mutation

Characteruzed by marked hyperCa, hyperparathyroidism, diffuse parathyroid hyperplasia, and skeletal underminerization

Typically lethal unless total parathyroidectomy performed within initial weeks of life

Autosomal Dominant Hypoparathyroidism (ADH)

Heterozygous activating missense mutation of human CaSR

Inhibits PTH secretion, reduces Ca reabsorption at an inappropriately low serum Ca conc. Ca homeostatic system adjusted to a lower Ca conc ( EC50)

Leading to hypoCa, relative hypercalciuria and inappropriately low PTH

HypoMg and hyperphosphatemia

Asymptomatic

Attempt to normalize Ca w calcitriol marked hypercalciuria, nephrocalcinosis and nephrogenic DI

Extracellular CaSR: therapeutic implications

CaSR responds to many polycationic ligands, including Ca 2+ , Mg 2+,

Gd 3+ and polyamines (neomycin and supermine)

Also activated by aa, esp aromatic aa

Potential therapeutic target for disorders w receptor inappropriately overactive or underactive

Some cpds developed w aim of either activating (calcimimetics) or inactivating (calcilytics) the CaSR (agonists or antagonists)

Calcimimetic agent, oral NPS R-568 successfully inhibit PTH secretion in intro and in subjects w primary hyperparathyroidism, parathyroid carcinoma, uremic hyperparathyroidism

Site of action – within and specific for the seven-membrane domain

CaSR antagonist by decrease urinary Ca excretion could be useful for Px of Ca-containing renal stones

Catalytic drug, NPS 2143 increase endogenous PTH secretion leading to a significant increase in bone turnover, potential candidates for the Px of osteoporosis