Download Primary Oxaluria

A Case of Mushroom
Identification Error
Dr. Dailin Li, VGH, Clinical Chemist
BCSLS, September 26, 2015
Case History
• 35 year old male presents to VGH ER on
October 7, 2014 with severe vomiting, diarrhea
and abdominal cramps, approx 1 day after
eating what he thought were magic mushrooms
that he had picked in a public grassy area.
• Previous History: Mental health issues and
polysubstance abuse. He had ordered
hallucinogenic mushroom spores online and
spread them in this public lawn sometime before
and came back to reap his harvest. He became
very sick for his efforts.
What are magic mushrooms?
There
are 200
different
species
What is the magic ingredient?
Psilocybin
Psilocin
What does it do?
• Psilocin is the active drug which has
hallucinogenic effects. Works via serotonin
receptors in brain and also increases CNS
dopamine levels.
• First described in 1799 in European literature
after a family accidently ate mushrooms
containing this substance causing uncontrollable
laughter in their child. However these have been
used in many cultures long before this date
• Effect can last several hours
• Drug not addictive due to tolerance and less
effect after repeated use.
Problem!
• Can be misidentified as in this case, with
other similar looking mushrooms. You
have to know what you are doing.
• This patient suspected he picked a
poisonous mushroom not one containing
psilocybins
• The toxin in these mushrooms are called
amatoxins
Selected lab results
Initial:
Creatinine
HgB
INR
Albumin
AST
ALT
TnI
Bili, GGT, ALKP, LA
232
206
1.3
55
372
545
0.55
Normal
Selected lab results
48 hours later:
Creatinine
HgB
INR
Albumin
AST
ALT
68
146
2.3
28
3900
6600
Amatoxin
• 10 known amatoxins all
consisting of 8 aa cyclic
structure with different
side chains attached
• Toxic effect related to
RNA polymerase
inhibition (mRNA,
microRNA, snRNA)
• Cell metabolism stops
and cells lyse
• Lethal adult dose 7 mg
Amanita phalloides
• Similar to edible
mushrooms
• May be responsible for
deaths of Emperor
Claudius and Pope
Clement VII
• Toxin: alpha amanitin
• 35 species of mushroom
contain amatoxins
• 6000 cases/yr in the US,
2 deaths in US/yr, 20 in
Europe
Clinical Effects
• The liver is the principal organ affected as it is the organ
which is first encountered after absorption in the
gastrointestinal tract.
• Amatoxins can be absorbed through the skin and also
inhaled, thus affecting other organs such as the kidneys and
heart, are susceptible.
• Amotoxins may cause irritation of the respiratory tract,
headache, dizziness, nausea, shortness of breath, coughing,
insomnia, diarrhea, gastrointestinal disturbances, back pain,
urinary frequency, liver and kidney damage, or death if
ingested or inhaled.
• Most severe effects are toxic hepatitis with centrolobular
necrosis and hepatic steatosis, as well as acute
tubulointerstitial nephropathy, which altogether induce a
severe hepatorenal syndrome.
Treatment
• Poison control centre and experts from
California consulted
• Cholecystostomy drain inserted to cut off
enterohepatic recirculation of the drug
• Milk thistle extract (experimental antidote) was
not available
• Lab results were monitored
• Bile and serum/plasma samples saved for future
studies
One week later
• Creatinine, HgB, bilirubin, INR, lactate all normal
• AST
• ALT
30 (<38)
498 (<80)
• Albumin
30 (34-50)
• Alkp
152 (30-135)
Patient discharged after total of 9 days in hospital and
followed up as out-patient.
Bile drainage tube still in place (Nov 13, 2014), will be
removed shortly. All lab parameters one month after
ingestion are normal except for increased WBC
Lesson of the day
• Beware of the mushrooms that you ingest
• There may be pleasant or very unpleasant
outcomes.
Two Short Stories About Long
Term Problems: One Happy and
One Sad
Dr. Dailin Li, VGH, Clinical Chemist
BCSLS, September 26, 2015
Case 1: Primary Hyperoxaluria
Case History
• 18 year old female with renal failure due to
bilateral nephrocalcinosis
• Past History: Presented at age 1 with
kidney stones and diagnosed with primary
hyperoxaluria type 1. Confirmed by liver
biopsy and genetic testing. Mother and
father were both carriers of AGT mutations
(alanine glyoxalate aminotransferase)
Initial Treatment
• Multiple lithotripsy treatments throughout
life to disintegrate calcium oxalate stones
• To minimize problem also placed on
hydration therapy, vitamin B6, potassium
citrate and magnesium oxide.
• Now on dialysis
• Next step liver and kidney transplant
Key Lab Results
• Creatinine:
112 umol/L June 2013
440 in January 2014
750 in February 2014 (dialysis
started)
• Urine oxalates: 1000 – 2000 mmol/day (< 400)
• Plasma oxalates: 90 umol/L (normal <2). Usually
max at 6 umol/L until kidney shuts down.
• Hematology: Anemic (HgB 80 – 90)
Defect in Primary Hyperoxaluria Type 1
Pyridoxine
Pathophysiology of PH1
• Autosomal recessive disease, defective
glyoxalate metabolism (liver peroxisome AGT).
• Prevalence: < 3:1,000,000
• Cause of 0.7% ESRF in pediatric cases in NA;
13% in high prevalence countries such as
Tunisia
• 2 mechanisms: decreased enzyme activity
(70%) or decreased trafficking (30%) of enzyme
into peroxisome (goes into mitochondria instead
where it serves no purpose)
Consequences of PH1
• Urine saturated with calcium oxalate leading to stones. (hydration,
citrate and magnesium used to improve solubility).
• Also high concentration in proximal tubular cells of the kidney where
it is toxic. Enhanced free radical injury and nephrocalcinosis.
• As kidney GFR drops systemic CaOx deposition begins to occur. If
kidney function intact plasma oxalate will only increase to about 3X
normal. Once kidney reaches ESRF increases to 40 – 50 X normal
as in this case
• First symptoms in most by age 5 (range 1 month to 50 years). ESRF
by age 25 in 50% of patients
• Most severe form present with renal failure by 4 months, systemic
oxalosis, anemia, metabolic acidosis
Systemic Oxalosis
• Sat’n at >30 umol/L of plasma oxalate.
• Deposition in every organ of the body except
liver
• X-ray shows calcium oxalate deposition within
bone appearance
• Oxalate osteopathy: pain, diffuse
demineralization, fractures and EPO resistant
anemia
• Other sites: retina, arteries, peripheral nerves,
myocardium (conduction block), thyroid, skin
Treatment Strategies
• Pyridoxine (Pharmacologic doses) works in
some depending on residual AGT activity
• Enhance CaOx solubility: fluid, citrate,
magnesium
• Diet: avoid beet root, spinach, rhubarb, ice tea
• Lithotripsy (caution, can damage kidney)
• Dialysis: CaOx will continue to accumulate
despite treatment
• Kidney transplant: Works for a short while
• Kidney liver transplant (1st performed for PH1 in
1984). Must do total liver.
What Happened to Our Patient?
• April 14 2015 combined kidney liver
transplant performed.
• Patient discharged on April 28th
• Meds: tacrolimus, MPA, prednisone and
sodium citrate
• Monitoring continuing 2 X / week
Most Recent Results (May 8)
• Plasma oxalate (Mayo): 3 – 6 umol/L (<2)
• LFT: ALT/AST normal, ALKP sl. inc.
• RFT: Cr and Urea normal, electrolytes N
• Urinalysis: +1 protein, +3 HgB, +2 WBC
• Hematology: WBC 12, HgB 94
Long time required to decrease CaOx crystal
accumulation in tissues.
Prognosis: 80% 5 yr graft survival. There is hope!
Case 2:
Pseudohypoparathyroidism 1B
Case History
• 29 year old female hospitalized for the past year
due to persistent incapacitating bone pain
• Difficult sitting (5 minute max), turning in bed,
can’t walk to bathroom, pain with light touch,
difficulty holding telephone, typing causes pain,
phone vibration causes pain, pressure on heel
cause pain.
• Now deconditioned with Cushingoid features
secondary to steroid therapy
• Problems first diagnosed at age 15 when she
presented with hypocalcemia
Initial Lab Findings
October 2007:
• Calcium 1.45 mmol/L (2.1 – 2.5)
• Phosphate 1.95 mmol/L (0.8 – 1.45)
• PTH 82.4 pmol/L (1 – 11)
• TSH 5.7 mU/L (0.3 – 4.2)
Treatment: Active Vitamin D and Calcium
Since 2007 patient has had 300 calcium
measurements and about 600 PTH levels
done (200 in the past year)
Mechanism of Action of PTH
• PTH binds to a G protein-coupled receptor.
• Binding of PTH to its receptor activates 2 signaling
pathways:
- increased cyclic AMP  (+) PKA
- increased phospholipase C  (+) PKC
• Activation of PKA appears to be sufficient to
decrease bone mineralization
• Both PKA and PKC activity appear to be required for
increased reabsorption of calcium by the kidneys
Actions of PTH: Bone
PTH acts to increase degradation of bone (release of
calcium).
• Rapid action
• Delayed action
– causes osteoblasts to release cytokines, which stimulate
osteoclast activity
– stimulates bone stem cells to develop into osteoclasts
• Net result: increased release of calcium from bone
• Effects on bone are dependent upon presence of
vitamin D
Actions of PTH: Kidney
• PTH acts on the kidney → the reabsorption of
calcium ↑ (excretion↓).
• Excretion of phosphate ↑ excretion of H +↓ (more
acidic environment favors demineralization of
bone)
• ALSO, stimulates transcription of 1-alpha
hydroxylase for Vitamin D activation in kidney→the
active metabolite of vitamin D3↑ (required for
calcium absorption from the small intestine, bone
demineralization).
• NET RESULT: increased plasma calcium levels
Regulation of PTH Secretion
• PTH is released in response to changes in
plasma calcium levels (negative feedback).
– PTH cells contain a receptor for calcium,
coupled to a G protein.
– calcium↑→ Gq → PLC → IP3 → calcium
inflow↑，ER calcium release↑→ PTH↓
• Also, vitamin D↑，Mg2+↑, P↓, somatostatin
→ PTH↓
PTH,
Calcium &
Phosphate
Physiological Response to Hypocalcemia
Causes of Hypocalcemia
Hypoparathyroid
Nonparathyroid
PTH Resistance
Postoperative
Vitamin D
deficiency
Pseudohypoparathyroidism
Idiopathic
Malabsorption
Post radiation
Liver disease
Kidney disease
Vitamin D
resistance
Pseudohypoparathyroidism (PHP)
Pseudohypoparathyroidism (PHP) is characterised by hypocalcaemia,
hyperphosphataemia and elevated levels of serum parathyroid hormone (PTH).
Besides PTH resistance, affected individuals may show
distinctive but variable features. These clinical findings are
termed Albright’s hereditary osteodystrophy (AHO).
Brachydactylyhands/feet
short stature, obesity,
short limbs
round face,
mental retardation
Characteristic ‘dimpling’
replacing the knuckles
PHP variants
PHP
(PTH resistance)
+
AHO
phenotype
PHP type 1a
AHO
PHP
phenotype
(PTH resistance)
PPHP
PHP type 1b
Pseudopseudohypoparathyroidism
Parathyroid hormone
PTH is synthesised by the parathyroid glands and regulates calcium and
phosphorous concentrations in extracellular fluid by acting on target organs.
In PHP, the biochemical characteristics are caused by end–organ resistance to PTH
rather than deficiency of PTH.
The PTH normally mediates its actions via a
Gs-coupled receptor.
In PHP hormone resistance is due to a
deficiency of the Gs subunit.
PHP 1b
• Localized resistance to PTH, mainly kidney
• Manifests as hypocalcemia, hyperphosphatemia,
and elevated PTH.
• About 70% will have elevated TSH due to TSH
resistance
• Prevalence unknown
• Usually diagnosed in children presenting with
symptoms secondary to decreased calcium:
numbness, seizures, tetany, cataracts and dental
problems. Also bone problems with decreased
bone density secondary to increased PTH
PTH 1b (Cont.)
• Most cases are sporadic
• 70% have sporadic or genetic inherited
methylation defects at the GNAS locus on
chromosone 20 resulting in the failed
expression of the G proteins in kidney cells.
Passed from the mother, not the father if
genetically determined.
• Biochemical proof of resistance confirmed by
injecting PTH and measuring urinary cAMP
and phosphate. Both fail to increase in
PTH1b
GNAS locus
•
GNAS is a complex imprinted locus on 20q13.
•
Encodes the Gs subunit, which is generated from the most downstream
promoter (exon 1).
•
Gs is imprinted in a tissue-specific manner, being expressed primarily from
the maternal allele in certain hormone responsive tissues, such as the renal
proximal tubules.
•
PHP type-1b is associated with epimutations at the GNAS locus on
chromosome 20q13.
GNAS locus & PHP-1b
Familial PHP-1b
Loss of imprinting (methylation) at GNAS exon 1A.
This epigenotype has been associated with maternally inherited microdeletions
in STX16 gene.
Sporadic PHP-1b
Variable GNAS imprinting defects that may involve the upstream DMRs NESP55 &
NESPAS, in addition to GNAS exon 1A.
Treatment
• Maintain normal calcium and PTH levels
with calcitriol and calcium
supplementation.
• Treat with thyroxine if TSH is elevated
• Biochemistry should be monitored
annually. What about our patient?
• Treatment is lifelong but prognosis for
normal life expectancy is good. What
about our patient?
Present Treatment
• Confined to bed due to bone pain (not joint pain)
• Meds: hydrocortisone (70 mg/day), ketamine,
gabapentin, methotrexate, clonidine, dalteparin,
hydromorphone, amiloride, thyroxine, calcium
carbonate, calcitriol
• Daily blood tests, leading to iron deficiency
anemia. PICC line to inject medications and to
draw samples for blood testing.
• Long term prognosis??? Presently a tragic
situation.